This study examined the effects of the Nirvana Fitness (NF) program on state body appreciation (BA) and its correlates, as well as the mechanisms that could explain these changes. The study participants were allocated to NF (n = 21) and functional training (control, n = 22) groups and participated in an 8-week exercise intervention. The mean age was 24.4 ± 6.7. The participants filled out online questionnaires on state measures of BA, body surveillance (BS), functionality appreciation, body–mind connection, mindfulness in physical activity (SMS-PA), intrinsic exercise motivation (IM), satisfaction of basic psychological needs, and perceived physical fitness (PPF) immediately after the first and last sessions. The results revealed a significant improvement in state BA and its correlates in both groups, with no changes in PPF in the NF group or IM in either group. An interaction between group and time effects was revealed in a change of relatedness, indicating a stronger effect in the NF group. Positive changes in SMS-PA, BS, and satisfaction of the need for relatedness significantly predicted improvement in state BA. These findings highlight the importance of targeting mindfulness, body surveillance, and relatedness during physical activity in interventions aimed at promoting positive body image in university-aged women.