Nearly half of America's youth (aged 12-21 years) are not vigorously active on a regular basis. Physical activity declines during adolescence, when physical education and youth sports become less available, and school, work, and less-active leisure activities become more important.  Regular physical activity should be encouraged for all children as a form of preventive healthcare. Physical activity performed during youth will improve quality of life during adulthood, and also reduce morbidity and mortality secondary to heart disease and other chronic illnesses.