Modifying patients' sedentary lifestyle, a risk factor for many chronic diseases, is a challenge to health professionals. Although physicians can play a vital role in promoting physical activity among sedentary patients, the prevalence of physician-based exercise counseling is low. This paper presents a review of studies that have targeted physicians as agents of behavior change. Changing sedentary behavior is more likely to be effective when the intervention is grounded in theory. This paper outlines an integration of two theoretical models that have potential for enhancing behavior change, and it describes specific techniques for physicians interested in promoting a more active lifestyle among their patients.