The purpose of this study was (a) to test a hypothesized model of motivation within the context of conceptual physical education (CPE), and (b) to explore the strength and directionality of perceived competence for physical activity as a possible mediator for health-related fitness knowledge (HRFK) and physical activity behaviors. High school students (N = 280) at the end of a CPE course completed the following: Behavioural Regulation in Exercise Questionnaire-2, Godin Leisure-Time Exercise Questionnaire, Perceived Competence Scale, and a HRFK Questionnaire. Structural equation modeling analysis was used to explore the relationships between the variables of HRFK, perceived competence, motivation, and physical activity. The analysis resulted in a modified model that showed a relationship between perceived competence and physical activity, mediated by introjected and identified regulation. A relationship also existed between HRFK and external regulation indicating students felt controlled. Suggested value-promoting activities could help students value concepts being taught.