Research shows regular exercise/physical activity provides substantial benefits in reducing morbidity and mortality from several chronic diseases in adults, particularly cardiovascular disease. Observations on levels of fitness and activity of children are just being developed with regard to cardiovascular risk. Current studies indicate that today's children are probably less fit than children 20 years ago. Children are heavier and tend to be more overweight and sedentary than earlier. The relationships between fitness and cardiovascular risk factors in children are very similar to those in adults. Those children who perform better on standardized fitness tests have more favorable body composition and lipid profiles. Because cardiovascular risk factors, including obesity, tend to track from childhood to adulthood, programs to increase regular physical activity in youths hold promise in reducing adult cardiovascular diseases. Positive long-term lifestyle changes need to be established early. Data from the Heart Smart Superkids/Superfit exercise program show that comprehensive school-based health promotion and education interventions can improve fitness in children and ultimately yield improvements in risk factor profiles.