The paper presents evidence that moderate forms of physical activity (such as walking and bicycling), when engaged in regularly, can have important beneficial effects on public health. It finds evidence that walking and bicycling are critically important exercise behaviors for improving public health, that urban form affects the frequency of walking and bicycling as a form of physical activity, and that the public health considerations outlined in the article should reorient planners’ thinking toward the realization of health-promotive environments.