Physical activity is essential to promote children's health and well-being. Increased sedentary behavior in children is a factor contributing to the escalation in childhood obesity in the general population. Clinical conditions, particularly physical disabilities, which reduce physical activity, may also lead to a higher risk of being overweight or obese. This paper reviews physical activity and sedentary behavior and illustrates how habitual (daily) physical activity, motor performance, and the capacity to be active are distinct and important aspects of a child's activity behavior. Positive health outcomes are linked to achieving adequate habitual levels of physical activity. This paper also highlights how pediatric therapists can promote health for those children who are already overweight or obese or are at higher risk of being overweight or obese. Physical and occupational therapists are encouraged to embrace a broad perspective of physical activity and extend children's therapeutic and health-promotion programs to include assessment of habitual level of physical activity and sedentary behavior, and promotion of recommended levels of daily physical activity. This role can also be extended beyond the area of disability.