Most of the data obtained in studying mental toughness has come from athletes, coaches, and sometimes parents. The purpose of the present investigation was to explore sport psychologists’ experiences of building mental toughness and their perceptions of how coaches can build mental toughness in their athletes. A phenomenological approach to qualitative research guided the study. Semistructured qualitative interviews with 15 sport psychologists were conducted. A concept map was developed that illustrates the theme and subthemes that emerged from analysis of the interviews. As indicated, sport psychologists felt that coaches could build mental toughness in their athletes by behaving mindfully, which included putting athletes under adverse situations and providing (teaching) them with the mental skills to effectively cope with these adversities. These results both confirm and extend existing research on how to build mental toughness.