During the last decade our concept of what "physical fitness" means has undergone a major change. Traditionally the "physically fit" child was one who had obvious motor (or athletic) abilities, ordinarily defined by such parameters as muscle strength, agility, speed, and power. But the high levels of power, speed, and agility necessary for success in most competitive sports have little or no relevance in the daily lives of most adults. Today, the words "physical fitness" imply optimal functioning of all physiologic systems of the body, particularly the cardiovascular, pulmonary, and musculoskeletal systems.1 DEFINING PHYSICAL FITNESS Physical fitness is now considered to include five components: muscle strength and endurance, flexibility, body composition (ie, degree of fatness), and cardiorespiratory endurance. Good cardiorespiratory endurance may be associated with a lessened chance of disability or death due to cardiovascular disease. Schools in the United States have traditionally emphasized sports such as football and baseball, both of which require agility and skill but are not particularly fitness enhancing. Aerobic activities (eg, activities requiring maintenance of 75% of maximal heart rate for 20 to 25 minutes), if performed at least three times a week, can lead to enhanced cardiorespiratory endurance. This improvement in fitness can be achieved by swimming, running, bicycling, field hockey, aerobic dancing, fast walking, etc. SCHOOL PROGRAMS Unfortunately, just as the understanding of the importance of health-related physical fitness has become widespread, our ability to direct youth activities toward fitness is being countered by several new pressures: (1) Financial strains may lead public school systems to reduce physical education budgets.