The US surgeon general recommends a minimum of 30 minutes of physical activity a day for adults to reduce the risk of chronic disease and an early death. Yet only about 1 in 4 American adults meets that recommendation through leisure-time physical activity and/or conscious exercise. One result is the so-called obesity epidemic, but a sedentary lifestyle also increases the risk of chronic diseases, such as diabetes, cardiovascular disease, osteoporosis, and cancer. We must create environments in which physical activity becomes a routine part of the day for more Americans. Encouraging routine walking and bicycling appears to be especially promising because of a growing understanding of how to create bicycle- and pedestrian-friendly settings. Everyone, not just those working in public health, must ally themselves with community leaders to pursue programs and policies to create settings with 4 key attributes: more compact neighborhoods with a mix of land uses; a comprehensive network of pathways, trails, bike lanes, and mass transit to allow "active" transportation; site designs that welcome cyclists and pedestrians; and an umbrella of safety that encourages people to get out of their cars. Many specific resources and programs are recommended to advance this agenda. Finally, we all must become role models by walking and cycling whenever possible and inviting others to do so with us.