RecruitingArlington Aging StudyThe goal of this observational study is to learn about the mechanisms causing functional decline with age, using magnetic resonance imaging, exercise science, integrative physiology, neuroscience, and remote monitoring. Specific aims include: Aim 1: Advance knowledge of the biology of aging and its impact on the prevention, progression, and prognosis of disease and disability. Aim 2: Determine the effects of personal and societal factors on aging. Aim 3: Examine the influence of racial/ethnic and sex differences on the biology of aging and its impact on the prevention, progression, and prognosis of disease and disability.