Just over a quarter of a century ago, thought leaders in the aging research arena recognized that the promotion of increased physical activity was a relatively unexplored but potentially powerful avenue to promoting healthy aging.1,2 Since that mandate to examine the role of exercise in preventive gerontology was issued, and during the past decade in particular, a growing body of evidence has accumulated that has given legs to the hypothesis that the promotion of physical activity may be the most effective prescription that physicians can dispense for the purposes of promoting successful aging. Today it is recognized that virtually all of the diseases and conditions that lead to physical disability in older adults have as part of their etiology a component of personal lifestyle choices (eg, physical inactivity) in addition to biological aging and environmental exposure. Improving our understanding of the relative contributions of these factors to aging-related loss of independence and the subsequent development and implementation of prevention and treatment approaches is the essence of the present research mission for scientists working in the areas of geriatric medicine and gerontology.