Heidrick, Charles, authorGraham, Dan, advisorHenry, Kim, committee memberDik, Bryan, committee memberLi, Kiagang, committee member2019-06-142019-06-142019https://hdl.handle.net/10217/195235The benefits of regular exercise are immense. Among these benefits are lower morbidity and mortality rates and an improved quality of life. Currently in the United States though, most adults do not meet exercise recommendations; in addition, per capita health care costs have more than doubled since 2000, and nearly 30% of adults are obese. Exercise is a prime mechanism to improve the health of Americans, but current behavior-change models in this area only modestly predict exercise behavior. The lack of exercise enjoyment is a major barrier towards behavior change, and for many, exercise does not feel good. This dissertation describes an intervention that built off both the hedonic theory of motivation and past research in the area of affect and exercise. Both adults in the Northern Colorado area and students at Colorado State University were recruited to participate in an intervention with the goal of increasing exercise behavior by improving exercise-related affect. Seventy-four participants went through a 15-week period where their exercise behavior was tracked: at a baseline laboratory visit, those in the affective intervention condition learned how to make exercise more enjoyable and the importance of doing so, while those in the standard intervention condition set personal exercise goals. Participants in the affective intervention condition increased their exercise levels over baseline levels more so than participants in the standard intervention condition throughout each of the fifteen weeks, although a mixed model repeated measures analysis of variance showed that this effect did not reach traditional measures of statistical significance. Fitness level and exercise performance saw no significant changes from pre- to post-intervention testing in either group. Implications from this experiment extend from adding to past research in this area by adding a longitudinal affective intervention to the literature to creating a new, forward-thinking mechanism towards health behavior change. In addition, these results highlight the difficulty of behavioral interventions in exercise science without strong incentives for participants to increase their exercise behavior. Some of the reasons for that difficulty, such as participants' perceived lack of available time to exercise (the most commonly reported barrier), are discussed in this dissertation's discussion section.born digitaldoctoral dissertationsengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.Text