This study will enroll healthy, sedentary individuals. Participants will be randomly assigned to either a print-based, individually tailored motivational program or an enhanced version of the same program. All participants will attend a baseline study visit, which will include body measurements, physical activity assessments, and health and psychological questionnaires. A select group of participants will also take part in an exercise test. Participants will then document their monthly physical activity. Study researchers will use this information, as well as the completed questionnaires, to develop individualized reports, manuals, and tip sheets that include feedback and strategies for increasing physical activity for each participant. Materials will be mailed to participants 14 times throughout the year. Participants in the enhanced intervention will receive additional materials that focus on increasing social support, self regulation, and outcome expectations, as well as materials on how to effectively monitor physical activity levels. They will also attend one study visit to assess their goals with the research staff. At Months 6 and 12, baseline evaluations will be repeated and all participants will be interviewed to assess physical activity levels.