Early childhood education and care (ECEC) is a vital arena for addressing sustainability issues, since values, attitudes, and behaviors are founded during the early years. As sustainability crises intensify, research has shown that eco-anxiety is growing among children and youth. Besides sustainability knowledge and skills, ECEC teachers also need to support children's notions of hope and how to be change makers. In this way, they need to mobilize their own hopes and action competence. In this study, we explore what drives ECEC student teachers' future work with sustainability and how they build hope and action competence. The study was conducted within a qualitative paradigm with an online questionnaire directed at student teachers (n = 50) at two universities in Finland and Sweden. A reflexive thematic analysis was adopted. The results show six different themes that illustrate the professional, personal, external, and internal aspects that drive them to work for Early Childhood Education for Sustainability (ECEfS). Furthermore, through a theoretical lens, the results can be understood as an issue of care and of the relationship with oneself, the children, and the world. The results suggest some rethinking of how we can better prepare future student teachers in ECEC to engage in sustainability education.