Purpose: Comprehensive School Physical Activity Programs aim to maximize the application of skills learned in physical education (PE) in other settings. We investigated students' generalization of participation in fitness activities from PE to organized fitness programs during lunch recess. Method: Voluntary participation of 153 (74 girls, age 12.4 years) students from five schools in a fitness recess program before, during, and after a 12-lesson sport education fitness season in PE was assessed by gender and skill level. Moderate to vigorous physical activity was assessed through systematic observation. Results: After the sport education season, participation in fitness recess dropped from 41% to 9%, p < 0.001, effect size = 0.34. Average moderate to vigorous physical activity was higher in fitness (45%) compared with traditional recess (11%), p < 0.001, effect size = 0.50, irrespective of gender and skill level. Discussion/Conclusion: Generalization of participation in fitness activities from PE to lunch recess is a promising strategy to increase students' moderate to vigorous physical activity.