Although perceived control is a well-established predictor of cognitive aging, less is known about how and under what developmental circumstances these beliefs about personal influence may protect against cognitive declines. Our study examined light physical activity (LPA) as an unexplored mechanism that may link changes in two facets of perceived control (personal mastery, perceived constraints) to longitudinal trajectories of cognitive functioning. We also examined whether mediated pathways were moderated by age (i.e., differed across the adult lifespan). We analyzed two-wave, 9-year data from the national Midlife in the United States Study (