This randomized, placebo-exercise controlled trial found that 6-months of Kung Fu training improved enjoyment of physical activity more than the placebo-exercise intervention, while both groups improved perceptions of behavioral conduct and changed strategies for physical activity. Importantly, family support for physical activity declined in subjects who had more visits to health care professionals, which is worrisome, as this represents another risk factor for sedentary behavior in this vulnerable cohort that must be overcome for successful, sustained behavioral change. Programs supporting positive attitudes of both adolescents and their families toward physical activity will be necessary to optimize exercise adoption and adherence as a means to combat the obesity epidemic in childhood and adolescence.