- Arm I (mastery model health behavior educational intervention): Participants log on to the Guide to Health Project (GTH) website weekly and are provided access over a 24-month period to healthy lifestyle coaching modules and a completely individualized fitness program organized according to a mastery-model health behavior educational intervention. The mastery-model intervention comprises a 6-month behavioral initiation phase that includes an orientation and refinement of goals and expectations for each content area; a 6-month behavioral establishment phase comprising healthy lifestyle coaching modules focusing on physical activity and nutrition at least once a week; and a 6-month behavioral maintenance phase comprising a taper in the frequency of coaching sessions to once a month.