It is suspected that deficits in self-regulatory variables such as self-control (SC) – the ability to inhibit impulses, self-motivation (SM) – the ability to mobilize energy, self-efficacy (SE) – confidence in one's abilities, and stress are contributing factors to the high rates of inactivity among Canadians. The majority of research examining this topic adopts a unifactor approach leaving the interactions among these variables unexplored, limiting our understanding of self-regulation and consistent physical activity (PA). The present study aimed to adopt a multifactor approach to explore the interplay among SC, SM, SE, and stress when predicting PA behaviour. At intake, participants completed a baseline questionnaire assessing demographics, trait SE and SM. Over the next two days, participants completed items assessing state SC, SM, SE, stress, and PA duration and intensity. Monte-Carlo simulation power analysis determined the ideal sample size for detecting multiple interactions was 500 (N = 582). The results from the structural equation model revealed that the latent variable state multifactor self-regulation consisting of SC, SM, and SE mediated the relationship between stress and PA. Furthermore, this mediation effect appeared to be moderated by trait SE and SM. These results support the notion of a depletion effect of stress acting on individuals’ state multifactor self-regulation resources resulting in fewer minutes of and lower intensity during physical activity; however, this depletion effect appeared to be buffered by high levels of trait SM and SE.