Being physically active contributes to health throughout life. Schools can play a key role in developing students’ capability for lifelong physical activity (PA). The main purpose of this thesis was to explore how this capability in adolescents in the Netherlands can be fostered. It builds on the assumption that to develop agency for lifelong PA, adolescents need the ability to reflect upon their assets for PA, are actively involved in shaping PA experiences that are meaningful to them and are supported with making the transfer of these experiences to their own contexts. This is mirrored in the Health Promoting Schools approach, which supports children’s development by using the school setting to promote PA, and in the Salutogenic approach, focusing on identifying factors or ‘assets’ that enhance PA. Both approaches advocate a school climate empowering students to become agents in their own lives.  To investigate our assumption we performed four studies with secondary schools in the Netherlands. In the first study, we unpacked the concept of agency to argue the relevance of developing PA related student agency through enabling their autonomy and freedom to engage in PAs that fit their goals. In the second and third studies, to inform PA-enhancing strategies, we developed and applied a procedure for two action research methods, the Structured Interview Matrix and Photovoice. This procedure enabled students to express their perspectives on PA and deliberate with peers. Ninety-three students from four schools aged 12–14 participated in two group sessions, discussing four asset categories derived from the literature: talents, passions, the social environment and the physical environment. The analyses of students’ perspectives show that: a) they need to perceive PAs as meaningful, appealing, contextually possible and manageable; and b) they use a variety of reasoning processes to decide whether to engage. In the fourth study, we analysed policy documents, interviews and focus groups with school managers, teachers and municipal sports professionals from six secondary schools. The results showed that, besides offering sufficient and varied PAs and PA opportunities, students’ reflection on the meaningfulness of these experiences and their transfer to other contexts is not embedded in the school curricular practices. We conclude that to educate students for the capability of lifelong PA, schools’ pedagogical approach should contain at least three elements: First, listening to students’ perspectives on their assets for PA and engaging them actively in shaping their PAs. Second, facilitating students to reflect upon these PA experiences to discover what makes them meaningful and fit their aspirations. Third, supporting them in contextualising and transferring their experiences to students’ daily life contexts. We, therefore, argue for a salutogenic approach in schools focusing on respecting and enhancing students’ agency concerning their PA thereby enhancing their capability to be physically active. This requires a school culture in which agency as a consistent pedagogical principle is embraced and practised. / The work of Gwendolijn Boonekamp was supported by a grant from the HAN University of Applied Sciences under decision number: 2017/1133.