IRCT201206021087N3 IRCT 2012-06-18 Tarbiat Modares University, Medical School promoting and maintaining exercise behavior in college students The effect of intervention based on Transtheoretical model using Self-determination theory to promote and maintain exercise behavior in college students 2008-09-24 anticipated 133 Complete https://irct.ir/trial/108 interventional Randomization: Randomized, Blinding: Not blinded, Placebo: Not used, Assignment: Parallel, Purpose: Prevention, Other design features: This study consists of two stages: 1) cross sectional study 2) interventional study. After determining the stages of change in exercise behavior in cross sectional study, students who were in preparation stage, were randomly allocated into experimental and control groups. N/A Exercise behavior. Intervention 1: In intervention group: TTM and Self-determination theory based intervention, including: 20 sessions 45 to 60 minutes lectures for 12 to 14 participants about increasing knowledge about exercise behavior, pros and cons in exercise behavior, goal setting in exercise, time management to fit exercise behavior in daily life and individiual interview,focus group discussion, role playing, simulation and video with a credible role model, rewading onself for activity and also sending SMS. Intervention 2: Control group: received classical intervention based on Guilan University of Medical Sciences strategies. In fact, this group did not receive any intervention by researcher.