There is evidence that participating in physical exercise reduces stress and the risk of many physical maladies. Exercise is also correlated with higher levels of approach motivation, or a tendency to approach challenge as an opportunity for growth or improvement instead of an opportunity for failure. To date, most research on this relationship has been correlational, so it is not clear whether increasing levels of exercise will also increase the level of approach motivation. If exercise is found to lead to the development of approach motivation, college students might be encouraged to exercise as a means of cultivating this motivational tendency. This is important because approach motives have been found to optimize the transition to adulthood. College students are presented with a plethora of challenges during this time in life, as they learn to live independently (away from home), explore their professional identity, and prepare for their professional lives. College students are more likely to be successful with these challenges if they employ an approach motivational style, as opposed to an avoidant style, which focuses on avoiding failure by reducing or avoiding challenge. Using an 8-week experimental design, participants were assigned to a control group or a treatment group of new exercisers to determine if exercise results in increases in approach motivation. Treatment group participants briskly walked either outdoors or indoors to determine if exercise context moderates the relationship. Given the body of research that suggests spending time outdoors amplifies the benefits of exercise, it was predicted that exercising outdoors (vs. indoors) would have a stronger positive impact on the relationship between exercise and approach motivation. The process model hypothesized in this study suggests that increases in exercise-specific self-efficacy contribute to increases in exercise-specific approach motivation and general self-efficacy, which, in turn, both contribute to increases in general approach motivation. This model was tested using multi-group path analysis. The multi-group path analysis indicates a good fit for the model, with the strongest paths being from exercise-specific self-efficacy to general self-efficacy, exercise-specific self-efficacy to exercise-specific approach motivation, and from exercise-specific approach motivation to global approach motivation. In the individual group path analyses, model fit and path contributions varied. Data from the non-exercising control group fit the model but none of the paths were significant. For the exercising control group the paths from exercise self-efficacy to general self-efficacy, and from general self-efficacy to general approach motivation were all significant, but the path from exercise self-efficacy to exercise-specific approach motivation was not significant. For the indoor exercising treatment group, the paths from exercise-specific self-efficacy to exercise-specific approach motivation and general self-efficacy, and from general self-efficacy to global approach motivation were all significant, but the path from exercise-specific approach motivation to global approach motivation was not significant. The outdoor exercising treatment group experienced significant improvements on all variables except exercise-specific approach motivation, but the data did not fit the model. The prediction that exercising outside would enhance the model outcomes was not supported, however, there may have been confounding variables. Small sample size, variability of outdoor activity location, and perceptions of campus safety may have diluted the treatment's effects. While previous studies have focused on the predictive nature of approach motivation for well-being, this study provides support for one's ability to "develop" approach motivation tendencies. For college students, walking programs may encourage the development of approach motivation at a time when opportunities to approach challenge are abundant. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]