Albert Bandura defines perceived self-efficacy as “people's beliefs about their capabilities to produce designated levels of performance that exercise influence over events that affect their lives.” Self-efficacy is just one of six constructs that SCT is based on; the other five include reciprocal determinism, behavioral capability, observational learning, reinforcements, and expectations. A lack of physical activity has been shown to contribute to heart disease, type 2 diabetes, and cancer even in individuals without any other risk factors. Social cognitive theory can be helpful in identifying motivating factors that lead to increased physical activity across age and gender. A study by Yael Netz and Shulamith Raviv in 2004 found positive correlations between high levels of self-efficacy when compared to physical activity. These findings suggest the best motivational method to increase the rate of physical activity is one that first increases perceived self-efficacy. As applied to public health campaigns, the first symptom to address is low levels of perceived self-efficacy rather than low levels of physical activity, since addressing the former may rectify the latter.