This paper presents findings on physical education (PE) trainees' and teachers' attempts to design and implement authentic curricular experiences, within the constraints of a neoliberalist context. It involved adopting a principle-based approach to promoting active lifestyles designed to align PE trainees' and teachers' health-related philosophies and pedagogies. The promoting active lifestyles (PAL) project was framed by social cognitive theory and the social ecological model and adopted a qualitative explanatory case study approach. Participants were secondary school PE trainees and teachers involved in a University-based Initial Teacher Education partnership in the East Midlands in England. The 32 participants were involved in professional development which included co-constructing and implementing PAL principles in the schools in which they were employed or undertaking their placement. All participants viewed the PAL principles positively and were able to implement at least some of them. Participants experienced unanticipated benefits beyond increased physical activity such as improved pupil behaviour. Many participants described transformative and enduring changes to their health-related philosophies and pedagogies. This low cost, flexible principle-based approach to pedagogical change addresses calls for evidence-based PE-for-health pedagogies and the development of possibilities that acknowledge the complexity of supporting physical educators to become more effective promoters of physical activity.