Sport and physical activity are crucial for social transformations, such as sustainable transformation. Drawing on evidence from positive and environmental psychology, this paper argues, within the context of sports, that the inner transformative qualities of athletes, the so-called inner sustainability, are crucial factors for the transition to a higher level of sustainable behavior. Evidence is presented that inner sustainability is connected to well-being and is a significant driver of sustainable behavior. This paper presents a road map for researchers investigating the internal transformative qualities in sports. Furthermore, examples of exercises to foster inner sustainability in sports are given. Given that sports often mirror sociopolitical dynamics, advocating for the enhancement of internal transformative qualities in sports becomes a pursuit of individual well-being and a conscientious effort toward the well-being of the entire ecosystem.