Physical activity levels, on average, decline during one’s life – particularly during adolescence. SCT can be used to explain the most prevalent contributing factors to this marked decrease in physical activity among adolescents and then develop appropriate intervention methods to best change this phenomenon. One study in particular addresses this subject through the SCT framework. Researchers mailed questionnaires to a random sample of 937 undergraduate students in the U.S. to measure the influence of personal, behavioral, and environmental factors on exercise behavior change. For both men and women, increased self-efficacy was the most important predictor in signifying positive changes to exercise behavior and physical activity.