Age affects an individual's fitness level due to natural physiological changes over time, including decreased muscle mass, bone density, and cardiovascular health. As people age, maintaining physical activity becomes increasingly important to counteract these declines. Older adults may experience slower recovery times and reduced strength, but consistent exercise can greatly enhance functional capacity, mobility, and overall health. Tailoring fitness routines to accommodate these changes helps seniors stay active and engaged, promoting longevity and quality of life.