Practitioners have the opportunity to enhance the health of their patients by improving exercise adherence through appropriate exercise prescription and monitoring. Regular physical exercise can prevent or improve many of the chronic health conditions commonly observed in clinical practice. Unfortunately, efforts to help patients adopt an exercise program are often unsuccessful. Researchers have shown that exercise self-efficacy is an important predictor of the adoption and maintenance of exercise behaviors. Self-efficacy is the belief and conviction that one can successfully perform a given activity. Patient compliance with exercise prescriptions is more likely to be successful if exercise self-efficacy is assessed and enhanced. Several questions arise for practitioners who are encouraging their patients to exercise: What are the determinants of exercise self-efficacy? How can exercise self-efficacy be assessed in the clinical setting? What can be done to enhance exercise self-efficacy? This article reviews the research literature addressing these questions and presents tools for assessing self-efficacy and prescribing appropriate exercise in the low-active adult population.