26Predisposing factors of perceived Physical Education (PE) ability and perceived PE 27 worth within the Youth Physical Activity Promotion Model are positively associated 28 with young people's daily physical activity. The aim of this study was to qualitatively 29 investigate the origins of students' perceived PE ability (perceived competence and 30 self-esteem) and perceived PE worth (attitude and enjoyment). Fifty-three PE 31 students, aged 12-14 years (mean=13.18), participated in semi-structured focus 32 group interviews, which were recorded, transcribed and analysed inductively and 33 deductively and represented as pen profiles. Analysis revealed three higher order 34 themes relating to perceived PE ability (external feedback, perceptions of 35 (in)competence and comparison against peers), and three higher order themes 36 underpinning perceived PE worth (PE teachers, expectancy-value relationship and 37 the physical experience of PE). PE should be perceived as interesting, relevant, and 38 meaningful by students and provide appropriate opportunities for success so as to 39 influence lifetime physical activity habits. Regular physical activity is an important contributor to a healthy lifestyle and can 52 provide immediate and long term health benefits (Powell et al., 2011; Reiner et al., 53 2013). Youth physical activity is inversely associated with clustering of 54 cardiovascular disease risk factors, diastolic blood pressure and waist circumference 55 (Ekelund et al., 2012;Lee et al., 2012). Biddle and Asare (2011) concluded that 56 physical activity can improve young people's psychological well-being and mental 57 health. Research therefore generally proposes that physical activity has numerous 58 physiological and psychological benefits and that it should be promoted in youth; 59 however, it is a consistent finding that youth do not engage in sufficient physical 60 activity to benefit their health (Bauman et al., 2012; Hallal et al., 2012). 61 62 School Physical Education (PE) is an important setting in which to promote youth 63 physical activity (Fairclough et al., 2012a; Hyndman et al., 2014; Lonsdale et al., 64 2013). PE offers a logical and plausible context for engaging youth in regular, 65 structured physical activity, whilst also developing knowledge, skills and attitudes to 66 enable participation in lifetime habitual physical activity (Heath et al., 2012; Trudeau 67 and Shephard, 2005). Therefore, for PE to be impactful, it should strive to influence 68 factors in adolescents' lives that are related to physical activity, for example 69 perceived competence and enjoyment (Hilland et al., 2011). 70 71 Welk's (1999) Youth Physical Activity Promotion Model (YPAPM) provides a useful 72 mediating variable framework to study physical activity correlates in a systematic 73 way (Baranowski et al., 2003). The model is based on Green and Kreuter's (1991) 74Precede-Proceed health promotion planning model, which was developed to provide 75 4 guidelines for establishing health education p...