There is a strong interest in improving the quality of anti-stigma contact-based interventions. Hence, some mental health anti-stigma campaigns offer prior training to their activists with lived experience of mental disorders. Additionally, collective mobilization seems to impact the identity and well-being of its participants. The main objective of this work was to understand the impact that activism training activities have on the internalized/self-stigma and well-being of activists being trained by the Obertament alliance against stigma in mental health. The Internalized Stigma of Mental Illness Inventory and the Pemberton Happiness Index were used to measure internalized stigma and well-being, respectively, at the beginning and the end of anti-stigma training courses. Sixty-eight activists receiving training were enrolled within a pretest, posttest, 1-group design. A total of 39 participants were included in repeated measures calculations. Twenty-seven participants did not complete the total training schedule and two more did not complete baseline assessment. Our results show generalized increases in well-being and decreases in the internalized stigma of participants. Additionally, a covariation between these changes was found. To further illustrate this covariation, separate groups were created using the baseline median. Hence, greater increases in well-being were for those participants with higher levels of baseline self-stigma and vice versa. This article shows the importance of addressing internalized stigma among mental health activists, thus boosting their recovery process.