This series of studies investigated the relationships between self-compassion, physical activity, and autonomous motivation for exercise. The purpose of Study 1 was to examine if autonomous motivation for exercise moderates the association between self-compassion and physical activity in Carleton University students using a cross-sectional design. The goal of Study 2 was to test the effects of a 5-day self-compassion writing intervention on autonomous motivation and physical activity in first year university students at Carleton University. Autonomous motivation did not moderate the relationship between self-compassion and physical activity in Study 1 (B = -1.04, SE = 1.88, t(383) = -0.56, p = .57, 95% CI = [-4.75, 2.65]). The self-compassion intervention in Study 2 did not affect autonomous motivation, self-compassion, or physical activity across time (p < .05, η2 = .01 - .24). Researchers should replicate these findings with larger sample sizes and better measures of self-compassion and physical activity.