Fueling Physical Activity with a Hybrid Motivational System: How Multiple Sources of Motivation and Experiences Promote Physical Activity Across Contexts and Time

Abstract

A critical feature of physical activity as a health behavior is that it must be performed regularly, and ideally over the course of one’s lifetime. However, only a small number of people engage in recommended amounts of physical activity to attain its health benefits, and interventions have had limited success in producing long-term behavioral adherence. Thus, more work is needed to identify constructs that produce lasting changes in physical activity. To understand physical activity as a repeated behavior, this dissertation presents a novel dynamic model of physical activity that describes how multiple sources of motivation work together in a hybrid manner to drive physical activity across contexts and time, and specifies how the outcomes afforded by physical activity help to sustain or undermine motivation for subsequent physical activity. Two studies were conducted to test a set of predictions derived from this model. First, a combination of intrinsic and instrumental motives is posited to be important for sustaining strong physical activity intentions, especially when one encounters barriers to physical activity. Study 1 used hypothetical scenarios to examine how these motives work together to strengthen physical activity intentions under various circumstances that differ in the extent to which they tempt participants to skip their planned exercise. Findings provided mixed evidence for the role of instrumental motivation, but suggest that intrinsic motivation may help sustain intentions across contexts by reducing the extent to which various barriers tempt one to skip their exercise. Second, affective and instrumental outcomes of physical activity are suggested to have distinct feedback loops that influence motivation for subsequent physical activity. Study 2 experimentally manipulated these different outcomes through an in-person exercise paradigm, and tested their relationships with motivation and intentions for continued exercise. A 2-week follow-up assessment examined the sustainability of each outcome as fueling sources of intentions over time. Findings provided evidence for distinct affective and instrumental feedback loops, but their implications for sustaining intentions over time are unclear. Recommendations for refining my model based on evidence obtained through Studies 1 and 2 are discussed alongside directions for future research.