Objective: To understand how competence, self-efficacy, enjoyment and motivation relates to physical activity behavior during transition from school to university. Participants: Health science students (n = 558) studying first year biology at an Australian university. Methods: Cross-sectional correlational survey design using five self-report questionnaires to establish relationships between a physical activity index and motivational variables. Results: Self-reported physical activity index scores of satisfactory or above were achieved by 80% of students with scores significantly higher for males than females. Enjoyment, self-efficacy and competence were predictive of physical activity index scores across genders. Conclusions: The physical activity index is a useful measure of activity dimensions across a variety of physical activities. Health science students need to underpin health messages with personal practice in modeling a healthy lifestyle. Universities have a special responsibility for building and supporting physical activity for all students, but especially for future health professionals.