Climate change is one of the most important problems facing the planet today and its effects on the planet and humanity are key issues for the current generation. It has been established that, in addition to many environmental disasters, the deterioration of the climate is also causing problems for the health of individuals. However, the psychological effects of climate change have not yet received the attention they deserve. Climate change has brought about an emerging mental health-related phenomenon called “climate anxiety”, which is defined as a ‘chronic fear and intense concern of environmental disaster’ (Clayton et al., 2017, p. 68) due to the effects of climate change. This study examines the views of young adults in Greece who take environmental action, on climate anxiety, the role climate change plays in their lifestyle, mental health and future decisions, how climate anxiety affects their participation in actions and its connection to the governmental response to climate change. Through the 13 interviews carried out, it can be seen that climate stress is not only real, but also particularly pronounced among environmentally active young people, significantly affecting their psychology, their general lifestyle, and their future decisions, such as the possibility of emigration and not having children. The anxiety and concern about the worsening climate, appears to be largely due to perceived government inaction, creating feelings of betrayal, frustration and anger among individuals. At the same time, climate anxiety is shown to be a significant factor in individuals’ decision to take action or not, as it can lead to either passivity and ‘psychological numbness’, or ‘productive anxiety’ and taking or participating in action.