Currently, only 32% of adults in the United States participate in regular physical activity. Several healthcare organizations, including the Centers for Disease Control and Prevention, the National Institutes of Health, and the American Heart Association recommend that adults engage in a minimum of 2 ½ hours of physical activity each week. In a previous study, individuals who received motivational print materials in the mail increased their weekly physical activity more than individuals who received no motivational materials or who received motivational support over the telephone. However, about half of those who were mailed the print materials still did not reach the recommended goal of 2 ½ hours of physical activity per week. The purpose of this study is to compare the effectiveness of an enhanced version of an individualized, print-based motivational program versus a previously tested print-based motivational program at increasing physical activity levels in sedentary individuals.