This introduction discusses the concept of affective health as a process of becoming in reciprocal relationships that is shaped by gender. This innovative approach aims to overcome the dichotomy between internal mental health and external socioeconomic causes of addiction, violence, and distress among men. Following the writings of Deleuze and Guattari, I develop a new understanding of masculinities as assemblages. I argue that there is a contemporary assemblage of masculinity that is based on modern individualism and the imperative to become a ‘self-made’ man, and that this compromises affective health in relationships more than ‘traditional masculinity.’ Based on an ethnographic comparison, this chapter reveals similarities and differences in young men’s trajectories in urban South Africa. It shows a unique way of presenting ethnographic data on gender through extended case studies of three male protagonists with different racial, ethnic, and religious backgrounds in postapartheid Cape Town. It is argued that the more invulnerable these White, Colored, and Black men tried to become, the more vulnerable they felt. Positive feedback loops spurred ‘affective storms’ that could result in surrender, help-seeking, and the transposition of masculinities and gender identity.