This study aims to determine how achievement goals, participation motivation and self-perception levels in physical activity environments relate to the flourishing of young adults. The general purpose of the study was also to examine differences in selected variables of young adults flourishing in physical activity environments. To achieve our aims, the recruited sample consisted of 580 young adult exercisers ranging in age from 18 to 40 years from fitness centers in Izmir, Turkey. Participants completed a personal information form, the Flourishing Scale, the 2 × 2 Achievement Goals Questionnaire for Sport (2 × 2 AGQ-S), the Situational Motivation Scale (SIMS), and the Physical Self-Description Questionnaire (PSDQ). We examined correlations, regressions, and path models with our measured variables. Flourishing relates significantly (p < 0.001) and positively with global self-esteem, the mastery-approach goal, intrinsic motivation, and global physical self-concept. Our path model suggested that the mastery-approach goal, intrinsic motivation, and global self-esteem partially mediated the relationship between global physical self-concept and flourishing. Our findings help to inform alternative approaches for cultivating exercisers’ flourishing. However, knowledge on how to support and develop flourishing is still under-researched in sport and exercise settings.