“Of all the causes which conspire to render the life of man short and miserable, none have greater influence than the want of proper exercise.”1 Recent epidemiological and clinical evidence support this observation by the 18th century Scottish physician Dr William Buchan. Studies suggest causal associations between regular physical activity and reduced rates of coronary heart disease, hypertension, non-insulin dependent diabetes mellitus, osteoporosis, colon cancer, anxiety, and depression.2 The most persuasive proof concerns coronary heart disease. People who are regularly active have about half the risk of those who are sedentary.3 4 Unfortunately, in the United States, Britain, and most other developed nations fewer than half of adults are regularly active.5 6 7 An estimated third of deaths from coronary heart disease in the United States (about 160 000 deaths per year) are attributable to insufficient physical activity.8 In response to the accumulated research and the widespread recognition that physical inactivity is a major public health issue, the United States National Institutes of Health convened a consensus development conference on physical activity and cardiovascular health last December. After two and a half days of scientific presentations and public …