How negative self-perceptions of aging relate to physical activity (PA) in older adults with arthritis is unclear. We examined whether general health mediated the relationship between Awareness of Age-Related change (AARC) losses and PA. We analyzed baseline data from a randomized controlled trial of a PA intervention for adults ≥60 years who self-reported PA, AARC, general health, pain, and social support. We evaluated point-biserial correlations between PA and other factors in participants with self-reported arthritis and developed a mediation model incorporating AARC losses, general health, and PA. We observed significant correlations between PA and general health, social support, and AARC losses in this physically active sample. General health mediated the effect of AARC losses on PA. While negative self-perceptions of aging were associated with less PA in older adults with arthritis, their impact was attenuated by general health. PA interventions for this population may benefit by targeting perceived general health.