Considering the limited field experience offered for preservice teachers to competently prepare them to implement the Comprehensive School Physical Activity Program (CSPAP) in schools, the purpose of this study was to examine the experiences of preservice and in-service teachers participating in a CSPAP infusion curriculum within a physical education teacher education program. Fourteen preservice teachers enrolled in an elementary physical education course implemented four CSPAP projects in four elementary schools as part of coursework. At the end of the project, the preservice teachers participated in focus group discussions and submitted self-reflection papers, while four in-service teachers who partnered in the program participated in interviews. Guided by Self-Determination Theory, results indicated that the preservice teachers developed competency and experienced autonomy in CSPAP implementation during field experiences. Furthermore, they felt a sense of relatedness with the teachers, classmates, and children throughout the program. Support for future implementation is spurred through the school community. In view of the increasing need for preservice teachers to be equipped with the skills to implement CSPAPs, infusing a CSPAP curriculum within a physical education course is viable to facilitate intrinsic motivation among preservice teachers to implement physical activity programs in the future.