This study investigated whether imaging a brisk walk once a day over a week could increase barrier self-efficacy among women who wanted to increase their exercise behavior. Participants (N = 32, mean age = 31.90 years, SD = 10.17) were randomly allocated to either an imagery rehearsal group or control group. The 4 min 10 s guided imagery script was designed to tap several sources of self-efficacy (e.g., performance accomplishments). The participants completed the Barriers Self-Efficacy Scale (BARSE; McAuley 1992) before and after the intervention. Scores increased significantly for the rehearsal group but not for the control group but these changes were no longer significant after controlling for pre-exercise levels. Results show preliminary evidence that imagery can be used by women to increase their barrier self-efficacy, which in turn may increase the likelihood of successful exercise adherence.