Peer modelling is the demonstration of particular behaviors that are learned observationally and is a powerful source of self-efficacy. This mode of learning has been very successful in increasing the consumption of new foods (36 subjects) and activity levels (100 subjects) in children. Based on this success, it would suggest that the investigators could confidently apply it to this study. Therefore the main objective is to examine the effect of a modeling intervention (DVD film) on self-efficacy and peak VO2 in obese youth during a maximal treadmill test. Models will demonstrate and articulate increased confidence to perform the test and offer a variety of strategies to cope with the maximal effort and overcome the associated challenges during the test (e.g. shortness of breath, sweating, and increased heart rate). The models will not be participants in the study.