The Importance Of Exercise and How To Incorporate It Into Your Lifestyle

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by Jeffry S. Life, M.D. Ph.D.

The United Nations, the World Health Organization, and 37 countries including the United States have proclaimed 2000-2010 as the Bone and Joint Decade to promote the importance of a healthy musculoskeletal structure for a lifetime. The number of people older than 50 will double between 1990 and 2020. Advances in medicine continue to make it possible for more people to live longer, but today most want to live stronger and maintain their quality of life. Each year, musculoskeletal conditions and injuries account for about 102.3 million visits to physician offices, 10.2 million hospital outpatient visits, 25 million emergency department visits, 3 million hospitalizations, and 7.5 million procedures, and they cost an estimated $300 billion.1 As the baby boom generation ages, people in their 50s begin to notice more aches and pains after performing the same activities that were painless in their 40s, and those in their 60s can't do as much as they did in their 50s. Roy Shephard, MD, PhD, professor emeritus of applied physiology at the University of Toronto, points out that, "Both aerobic power and muscle strength decline by as much as 10% for every decade of adult life, but a progressive exercise prescription can enhance function by 10% to 20%; thus, in terms of functional capacity, conditioning can reduce biological age by 10 to 20 years."2 In 1998, the American College of Sports Medicine issued its first position statement on aging and exercise,3 in which it recommended strength training for frail older people. Petrella says, "We now know that older patients can perform to very high levels, so exercise prescription does not differ for older and younger persons, and training effects for the elderly can exceed those of younger people at the upper end of VO2max." Exercise is the key to maintaining quality of life, as well as extending the number of years of life expectancy. It's never too late to start, and an early start is better. Even 90- and 100-year-olds can do strength training. Exercise is really a form of medicine that can prevent or treat many disabling or fatal diseases. Seventy percent of deaths (1.5 million) each year in the United States are a result of eight killers: heart disease, cancer, stroke, hypertension, chronic obstructive pulmonary disease (COPD), diabetes, and osteoporosis4. Other diseases treatable with exercise--obesity, arthritis, depression, and dyslipidemia--contribute considerably to disability and premature death The health rewards of exercise extend far beyond its benefits for specific diseases. Exercise reduces blood clotting, enhances self-image, elevates mood, reduces stress, improves appearance, increases energy, gives the feeling of well-being (probably by stimulating endorphins). It reinforces other positive life-style changes, such as healthier eating habits and smoking cessation5. It also stimulates creative thinking 6. Furthermore, the ability of exercise to restore function to organs, muscles, joints, and bones is not shared by drugs or surgery. Paradoxically, conventional medical practice favors physical rest and inactivity during recovery from illness. Aerobic Exercise vs. Resistance Training For many years doctors have advised middle-aged and older people to get plenty of aerobic exercise—that is, exercise that requires the rhythmic movement of their arms and legs. This form of exercise, which includes walking, jogging, swimming, bicycle riding and so on, has always been thought to be the best exercise to help prevent and/or treat heart disease. Doctors have traditionally discouraged people with heart disease or older people from engaging in strength training with weights or exercise machines because they believed that this would put dangerous stress on their hearts. Recently, an expert panel of scientists, organized by the American Heart Association, has finally put to rest that age-old myth that weight training and other forms of resistance exercise are bad for the heart. In fact, this committee has advised doctors to actually start recommending this form of exercise for their healthy older patients, as well as those with heart disease, including some people with recent heart attacks as long as they are closely monitored and supervised by experienced health professionals. Aerobic exercise and resistance training clearly work hand-in-hand to prevent, reduce, or even eliminate heart disease by preventing or controlling diabetes, high cholesterol and high blood pressure. Aerobic exercise does a great job lowering systolic blood pressure, and both aerobic and resistance exercise help reduce diastolic blood pressure. This makes it much easier for the heart to do its job of pumping blood throughout the body. Both forms of exercise also strengthen the heart muscle making it work much more efficiently. Obviously, this is great news. Now doctors can encourage their patients with healthy hearts (no matter what their age or gender) and those with unhealthy hearts (under medical supervision) to start using resistance training along with their aerobic training as an integral part of their heart-disease prevention and/or treatment program. The following table, by Pollock and Vincent, from The President’s Council on Physical Fitness and Sports Research Digest, is found in my article entitled “Why Everyone Should Lift Weights” in this website. This table helps us better understand the differences in aerobic (cardio) training and resistance training. Comparison of the Effects of Aerobic Endurance Training to Strength (Resistance) Training on Health and Fitness Variables Variable Aerobic Exercise Resistance Exercise Increases Bone Density Decreases Body Fat Increases Muscle Mass very little effect Increases Strength Decreases Insulin Response to Glucose Decreases Basal Insulin Levels Increases Insulin Sensitivity Increases HDL very little effect Decreases Resting Heart Rate very little effect Increases Stroke Volume of the Heart very little effect Decreases Systolic Blood Pressure very little effect Decreases Diastolic Blood Pressure Improves Cardio/Vascular Fitness Increases Endurance time Improves Physical Function Increases Basal Metabolism Dr. Kenneth Cooper, who coined the term aerobics in 1968 and a staunch advocate of aerobic exercise, now believes a mix of aerobic conditioning and strength training is the best exercise program for aging adults. He proposes an “aerobic-strength axis” with the balance changing depending on how old you are. At age 40 and younger, he suggests 80% aerobics and 20% strength; age 41 to 50, 70/30; 51 to 60. 60/40; and at 61 and older, 55/45. So he still favors aerobics, but the bias practically disappears after age 60. “A good rule of thumb, “ says Cooper, “is that you should always include at least 50 percent aerobic/endurance work in your personal fitness routine, regardless of your age and sports interest.” As individuals age they need more strength training. In Regaining the Power of Youth At Any Age, Cooper writes: “Up to age 50, people lose about four percent of their strength and muscle mass per decade. After that, the loss increases to about 10 percent per decade.” “By age 60”, he goes on to say, “the average man will have lost about one third of his muscle mass—unless he makes an effort to reverse the process through weight training.” Women have a similar decline as they age. Cooper still leans toward aerobics because he believes the supporting evidence at this time is stronger. He cites a number of impressive studies showing that endurance training slows the steady erosion of oxygen uptake capacity with age that appears to occur for both trained and untrained individuals. He cites one study, which indicates that it may even be possible to stop the decline with hard consistent training. That study, reported in the Journal of Applied Physiology, followed a group of track athletes, age 50 to 82, who remained highly competitive for 10 years – and found that their aerobic capacity remained unchanged during the entire time. Individuals who aren’t satisfied with a moderate level of fitness can take heart from a study published March 14, 2002, in the New England Journal of Medicine. The researchers concluded that exercise capacity is perhaps the most powerful predictor of mortality. They found a direct relationship between greater fitness and longer survival. Most previous studies have emphasized that the least fit have the most to gain from exercise, that the most striking reduction in mortality results when one becomes active and moves out of the poor fitness category. An earlier study reported in 1989 by the Institute for Aerobic Fitness in Dallas highlighted that those in the high-fitness group were only slightly less likely to die than those in the medium-fitness groups, but this study shows that people benefit in proportion to their level of fitness. As in other studies, the researchers found a "striking difference" in mortality rates between the least fit 25 percent and the next quintile of fitness. "This observation concurs with the consensus," the researchers wrote, "that the greatest health benefits are achieved by increasing physical activity among the least fit." They also demonstrated that there is a nearly linear reduction in risk with increasing quintiles of fitness. With each 1-MET increase in exercise capacity there was a 12 % improvement in survival. Participants whose exercise capacity was less than 5 MET were roughly twice as likely to die as those with exercise capacity of more than 8 Met. Absolute exercise capacity measured in METs predicted risk of death better than percentage of age predictions. In both healthy participants and those with cardiovascular disease, peak exercise capacity was found to be a stronger predictor of death than risk factors such as hypertension, diabetes, obesity, heart arrhythmia, high cholesterol, and even smoking. Poor fitness proved to be the deadliest risk factor of all. Lead author Jonathan Myers, a professor of medicine at Stanford University, told the Washington Post "No matter how we twisted it, exercise came out on top." Exercise pays big dividends. It’s even more important than smoking in its impact on life span. Greater fitness means longer life. What could be a bigger dividend than that? Doctors who don’t encourage their patients to exercise are missing the boat. Gary J. Balady, M.D., summarized the message in an editorial which accompanied the report: "The data from the study compel the clinician to go beyond the identification of risk to the initiation of interventions, such as the prescription of increased physical activity and exercise, in order to modify risk, particularly in patients with low levels of fitness." Benefits of Exercise Therapy for the Common Serious Diseases Coronary artery disease7-11. Coronary artery disease (CAD) is our number one killer, responsible for 2,000 deaths in the United States each day. About twice as many heart attacks occur every day. CAD claims many people who are at the peak of their career. Exercise combined with diet therapy can reverse established heart disease. Furthermore, exercise improves heart function, reduces several coronary risk factors (hypertension, high cholesterol, low high-density lipoprotein (HDL) cholesterol, and obesity), enhances psychosocial wellbeing after a heart attack, and improves survival. In summary, exercise is an effective strategy for preventing heart disease, and it is a beneficial, low-cost, pleasure-giving treatment without the side effects of drugs or the risks, pain, and expense of surgery. Cerebrovascular disease12-14. Vigorous exercise in early adulthood confers considerable protection from strokes in later life. This effect is independent of other risk factors. Furthermore, exercise is essential for restoring function following a stroke--again, a benefit not shared by drugs or surgery. Hypertension15-19. Substantial evidence shows that exercise is an effective treatment for mild and moderate high blood pressure and is a useful adjunct for the treatment of severe hypertension. Many patients who adhere to a regular, specifically prescribed aerobic exercise program can reduce their blood pressure without taking drugs. Thus, they avoid the potentially toxic effects and considerable expense of long-term drug therapy. Drug and exercise compliance are reported to be similar. Postexercise blood pressure reduction in normal and hypertensive patients disappears 2 weeks after exercise stops. The degree of blood pressure reduction depends on the type, duration, and intensity of the exercise, as well an individual's genetics. Therefore, the prescription must be carefully individualized. Among non-pharmacologic means for lowering blood pressure, physical activity provides better patient compliance and quicker results than weight reduction or alcohol and salt restriction. Diabetes20-22. Exercise can prevent or delay the serious complications of diabetes, namely, the vascular disease of the brain, heart, kidney, eyes, and legs that commonly occurs in diabetics who are under age 40. The same benefits of exercise are seen in those who develop the disease in later life. Exercise improves the abnormal blood lipid pattern and reduces the high blood pressure common in people who have diabetes. In addition, exercise increases insulin effectiveness and the metabolism of sugar, thereby reducing the insulin requirement, which in turn reduces the risk of vascular disease. Elevated blood insulin has been implicated in the pathogenesis of arteriosclerosis. The complexity of diabetes treatment requires a combination of methods to achieve healthy blood sugar levels and to prevent or reduce the serious complications of the disease. An exercise regimen, properly taught and followed, helps accomplish this goal and allows diabetic patients to lead healthy, active lives. Arthritis23-26. In patients who have rheumatoid or degenerative arthritis, exercise improves endurance, strengthens muscles, and increases joint flexibility and range of motion. These, of course, are benefits that drugs or surgery cannot achieve. Osteoporosis27-29. Osteoporosis affects 20 to 24 million postmenopausal American women and an unknown number of men over the age of 80. It results in musculoskeletal weakness, loss of height, bone fractures (primarily spine and hip), and painful disability. Two hundred fifty thousand hip fractures occur each year in the United States, resulting in 12,000 deaths and $11 billion in medical expenditures. Research indicates that regular exercise can prevent and control the disease. Dyslipidemia30-32. Abnormalities of blood fats (high total cholesterol and triglycerides and low HDL cholesterol) are major risk factors for vascular disease of the heart, brain, kidney, eyes, and legs. Regular exercise reduces total cholesterol and triglyceride levels and raises HDL cholesterol. Obesity33-36. The amount of body fat is a useful indicator of health and fitness, as well as an early warning signal of many serious diseases. Excess body fat is a risk factor for heart disease, hypertension, diabetes, many cancers (breast, prostate, colon, uterus, and gall bladder), and premature death from other causes. It appears that being overweight aggravates a very wide spectrum of diseases and is also a handicap to getting a job, obtaining admission to a university, and forming social relationships. The magnitude of the problem in the United States is greater than in any other country. Estimates of the number of overweight Americans range from 50 million to 200 million. The average American is said to have 20 to 30 lb of excess body fat. Daily, lifelong exercise is an essential strategy for achieving and maintaining optimal weight. Diet, though essential, cannot be relied on exclusively for successful weight loss and maintenance. Depression37-39. Depression, the most common mental disorder in America, affects approximately 5% (about 12 million) at any given time. Psychologists have observed that walking or running has both physiologic and psychological benefits for people who are depressed. These forms of exercise reduce depression and anxiety, increase feelings of wellbeing, improve tolerance to everyday stress, and improve the self-image of depressed patients. It is difficult to sustain depressed feelings while one is physically exercising. Furthermore, exercise stimulates the release of the "feel good" hormones (endorphins). One report38 concluded that walking or running while talking with depressed patients was more effective than talking and listening to them in an office because (1) the walking approach is non-confrontational--the patient and therapist are side by side, looking ahead rather than looking directly at one another; (2) the talking is being done in a less threatening setting; and (3) the patient is actively experiencing life rather than passively observing it in a chair. Cancer. There is evidence that physical activity reduces the risk for cancer of the left side of the colon40 and the breast41. COPD. Recent data42 suggest that adding an exercise component to the rehabilitation program for patients who have COPD results in physiologic as well as psychological benefits, even for those with severe air flow obstruction. A Plan for Therapy To be maximally effective for therapy or health enhancement, an exercise program must fulfill certain basic requirements: It must be a daily activity (7 days a week), it must be fun, not painful or excessively fatiguing, and it must fit an individual's preferences5-6. The selected activities must be readily available, not distant or difficult to reach, and preferably be close to the home or workplace. The clothes, equipment, and/or club membership associated with the activity must be inexpensive. Ideally, the activity should not depend on other people (team, class, or partners), but should permit group participation if desired. And finally, the activity must be suitable for lifelong participation. The major form of aerobic exercise should be (walking, running, cycling, swimming, or cross-country skiing). Variety is an important part of the prescription: At least two or preferably three different activities are recommended, for example walking-running-tennis or walking-cycling-swimming. The choice of exercise should be guided by individual preference and previous experience. Walking and running are most often recommended because they do not require special training or skills. They are inexpensive, readily available, safe, and suitable for doing alone or with others. The acronym DF ALIVE is helpful to guide one’s exercise program: Daily, Fun, Available, Lifelong, Independent, Variety, & Endurance. Encourage Lifelong Habits The daily goal is to exercise for at least 30 to 60 minutes (2% to 4% of the day) and to make a conscious effort to do body movement throughout 16 hours of the day (i.e., doing household chores, working, shopping, gardening, running errands, visiting, or socializing in an active manner5-6). Everybody should have an individualized lifelong exercise program designed to fit his or her lifelong situation and preferences. In recent decades, research has validated the effectiveness of regular exercise as a way to reduce and/or prevent age-related functional decline and reduce the risks of a sedentary lifestyle43. Most medical groups recommend regular physical activity44. People over age 65 carry the highest load of chronic disease, disability, and healthcare utilization45. Though many of these problems are preventable, primary care physicians rarely provide their older patients with an appropriate exercise recommendation that includes an individualized motivational message, a pre-participation evaluation to ensure a safe exercise program, and a tailored exercise prescription46. The first step in a pre-participation evaluation by your physician is to be evaluated for reasons not to be involved in exercise testing and training and to identify any risks or limitations relevant to an exercise program. An efficient screening questionnaire addresses previous exercise programs; present activity (frequency, duration, and intensity); existing chronic or acute disease(s), especially chronic obstructive pulmonary disease, cardiovascular disease, and extreme motor limitations because of severe arthritis; family history of cardiorespiratory disease; and coronary artery disease risk factors. Though most of the risk of exercise-related morbidity and mortality is associated with preexisting cardiac conditions, contraindications to exercise testing and training are the same for older and younger adults. Absolute contraindications to formal exercise testing include recent electrocardiographic changes or acute myocardial infarction, unstable angina, third-degree heart block, and acute congestive heart failure47. Relative contraindications to exercise testing include elevated blood pressure, cardiomyopathies, valvular heart disease, complex ventricular ectopy, and uncontrolled metabolic diseases. Physical Examination and Lab Tests The physical exam and laboratory tests focus on a patient’s functional abilities and/or limitations. A medical assistant, nurse, or other midlevel practitioner under a physician's supervision can usually accomplish most of the steps of the pre-participation exam. The average office-based evaluation takes about 20 minutes, though additional time is required if treadmill testing, bone mineral density scans, or respiratory function tests are needed. The physical examination should include vital signs and cardiorespiratory and musculoskeletal evaluation. Cardiovascular fitness. The American College of Sports Medicine (ACSM) recommends cardiac treadmill stress testing before commencing vigorous exercise (exercise intensity greater than 60% of maximal oxygen uptake) for men over age 40, women over age 50, and all patients who have cardiac risk factors with or without symptoms47. Treadmill tests, which can be used to estimate the patient's aerobic capacity, are useful for prescribing exercise intensity. If a treadmill test is unavailable, the Kasch pulse-recovery test can be performed in the office to give physicians a general idea of a patient's functional and aerobic capacities. The test is based on the principle that the better one's level of fitness, the sooner the heart rate returns to baseline after exercise. The patient's pulse and blood pressure are measured at rest and 1 minute after he or she has stepped up and down (with both feet) a 12-in. step 24 times per minute for 3 minutes48. To help patients adhere to this pace, setting a metronome to 96 bpm may be helpful. Respiratory function can be determined simply by measuring the patient's forced vital capacity and forced expiratory volume in 1 second. The Role Physicians Play in Prescribing Exercise Programs Medical students spend a year learning about pharmacology and they receive instruction on drug prescribing throughout their training. Often, the drugs they study will no longer be recommended by the time they are in practice. On the other hand, medical students are not instructed on how to prescribe exercise (or, for that matter, nutrition)—the best medicine of all. Physicians need more training in how to make best use of this powerful therapy. Physicians can successfully encourage increased activity by giving their patients a written exercise prescription along with printed advice on how to design a safe, enjoyable routine. Prescribing exercise is like prescribing medications, surgery, or other therapy—It is a thoughtful compromise between potential benefits and side effects. After careful consideration of these factors, the physician and the patient reach an agreement on the most effective plan. Important considerations include the goal of exercise (e.g., osteoporosis prevention, weight loss, strength improvement, marathon training) and patient preferences. Expanding on his or her current exercise habits is a good starting point because choosing activities the patient already enjoys improves adherence. Setting goals. The ACSM recently published separate position statements on exercise for healthy adults56 and older adults57. Kligman et al.58 have adapted these recommendations, combined with those from the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH)59, into a very helpful chart that outlines basic exercise prescriptions for a range of health and fitness goals. Basic Exercise Prescriptions for a Range of Health and Fitness Goals for Older Persons, Adapted From Federal Exercise Guidelines Fitness Dimension Disease Prevention Basic Health Fitness Performance Cardiovascular capacity Accumulate 30 min of physical activity most days Large-muscle repetitive exercise or equivalent sports activity, 20 min, 3x/wk Aerobic exercise or equivalent sports activity, 40-60+ min, 4-6x/wk Add competition and/or interval training Strength Include weight-bearing activity "Core four"* or equivalent program, one set, 8-12 or 12-15 repetitions at challenge weight,** 2x/wk, Pilates work*** Balanced whole-body free weights or machines, 1-3 sets, 8-12 repetitions reaching functional failure,++ 2-3x/wk, Pilates work Add ascending and descending pyramids+++ and muscle endurance or power training, Pilates work Flexibility Maintain range of motion by bending and stretching in daily activities 2-4 stretches after activity, 1 repetition, hold 30 sec 6-10 whole-body stretches before and after activity, 1-2 repetitions Add yoga, Pilates, and/ or facilitated stretches with a partner Body composition Men -- >5%-<25%>125-150 lb 12%-20% fat; maintain lean body mass at >125-150 lb 8%-15% fat Women -- >14<38%>90-110 lb 20%-30% fat; maintain lean body mass at >90-110 lb 17%-25% fat Balance and agility -- "Act like a child"; balance line; "Don't step on a crack"; brush teeth while standing on one foot Recreational sports (eg, tennis, biking); tai chi; social dance; therapy ball training Agility or skill sports (ie, surfing, skiing, skating); martial arts; performance dance; agility drills *Core four: double-leg press, chest press, latissimus dorsi pulldowns, abdominal crunch. **Challenge weight: the lift is difficult but can be accomplished. ***Pilates: a series of stretching and strengthening exercises performed on a mat without equipment, developed by Joseph Pilates in the 1930s. ++Functional failure: unable to complete another repetition without sacrificing form. +++Ascending pyramids: more weight is added to each set to cause fatigue with fewer repetitions; descending pyramids: weight is removed from each set to allow more repetitions until fatigue. Like the pre-participation medical evaluation, the exercise prescription should address the five major fitness components: cardiovascular fitness, muscle strength and endurance, flexibility, body composition, and balance and agility. Many older patients have low muscle mass and/or decreased strength, underscoring the importance of strength training. The ACSM recently added formal strength training recommendations to its exercise guidelines for adults56. Within the five categories, an individual and his or her physician should select the desired fitness level. The objective is to allow people to indefinitely maintain their current level of function and, ideally, help them reach the next category. The types and dosages of exercise will change as the patient's physiologic function changes. Selecting activities. An exercise program prescribed by your physician should address the type, frequency, duration, and intensity of physical activity for each fitness component. Though the type of exercise is often determined by available facilities and equipment, your preference should carry considerable weight. For example, if you enjoy golf you should be encouraged to occasionally substitute this activity for a treadmill and resistance training session. Your physician should balance the benefits of each exercise mode with the your health goals and physical limitations. For example, walking, bicycling, and swimming provide excellent cardiovascular benefits, but the weight-bearing nature of walking provides a greater stimulus for bone mineral deposition than cycling or swimming does. On the other hand, swimming is better tolerated by people who have joint limitations. Cross-training is an effective compromise among several appropriate options. You can mix exercise modes within any given week or within a single session. Cross-training programs help prevent boredom, condition more muscle groups, and reduce the risk of overuse injury. Determining frequency, duration, and intensity. Exercise variables can be manipulated to enhance compliance, but the dose-response relationship must be considered. Though exercising more often, longer, or harder affords greater conditioning, the relationship between effort and outcome is rarely linear. The point of diminishing return is often reached even before individuals approach levels that pose a risk of excessive fatigue or injury. Surprisingly little exercise is required to meet the recommendations for disease prevention (CDC-NIH recommendations)59. Physicians and exercise physiologists often make frequency and duration recommendations at minimal and optimal levels, with instructions to perform the minimal exercise during the busiest weeks and meet the optimal criteria on all others. Exercise intensity is always prescribed as a range (e.g., a target-heart-rate range of 120 to 145 beats per minute or muscle fatigue in 8 to 12 repetitions). Using an age-predicted target heart rate has limited value and is often misleading, especially as patients age, because 70% to 85% of age-predicted maximal heart rate is often off by 15 to 20 beats per minute. Physiologic change occurs when the body is exposed to stimuli greater than it can currently handle, a concept called “teasing the physiologic threshold.” The concept is useful even in balance and agility training. Many people underestimate their exercise capacity, considering physical activity to be uncomfortable, hazardous, or medically unwise. However, Fiatarone et al60 demonstrated the safety and effectiveness of a strength training program even for nonagenarians. The quantity and load of an exercise should be adjusted as function improved. An exercise prescription should involve monitoring or teaching patients to assess their own progress. MET levels are useful for setting exercise goals. A list of common physical activities classified by intensity in METs is available61. I have attached this article at the end of my article to help you design your exercise program. The Borg perceived exertion scale, http://www.cdc.gov/nccdphp/dnpa/physical/measuring/perceived_exertion.htm, is frequently used to evaluate aerobic exercise intensity; it can also be used to rate the intensity of resistance training and stretching. Maximal exertion on the Borg Scale is 20. Exercise physiologists often recommend aerobic exercise in the moderate to heavy range (13 to 15 on the Borg scale) for healthy young adults, and may modify their recommendations to light to moderate (11 to 13 on the Borg scale) for older adults. As function improves, increasing the intensity or duration of exercise should raise the challenge. In strength training, a common recommendation is to lift to muscle fatigue (inability to complete another lift while maintaining good form) in 8 to 12 repetitions. For older adults, 12 to 15 repetitions using slightly lighter weights may be more appropriate. Weight is increased when the patient can consistently complete 13 repetitions; then he or she repeats the process. The rate of improvement varies among individuals and may be slower in older adults. We have no control over our genetics and very little control over environmental factors, but the things that we can control—diet and exercise—can profoundly affect our longevity and quality of life. Exercise may be the closest thing we have to the fountain of youth. All we have to do is to “just do it.”