School physical education (PE) experiences play a critical role in adolescents' physical activity (PA) levels. Teachers are crucial to students' initial experiences in PA; however, limited research has explored teachers' perspectives about PA during PE using in-depth qualitative research techniques. We conducted interviews with 25 current Australian male and female PE teachers to investigate their perceptions about PA in secondary school PE (grades 7-12). Our findings indicated PA was a major focus for teachers during PE lessons; however, many physical and psychosocial factors underpinned practical classes. During PE lessons, PE teachers favoured game-based activities to promote PA while citing the traditional skill-drill approach as a strategy that limited PA. These findings highlight an ongoing shift in PE teaching towards a games-based approach and have several important implications for future teaching practice and research.