The primary goal of this article is to review theoretical models utilised in designing physical activity interventions for healthy adults. Physical activity offers numerous benefits for improved physical and psychological health. However, the majority of the population is sedentary and therefore at increased risk for morbidity and mortality. Many techniques have been developed for intervening with physical activity behaviours, some of which are based on theoretical models. While some of these models show more promise than others, no model is sufficient to thoroughly explain exercise behaviours or how to best intervene. In the final section, recommendations for future research are presented, and promising areas of development in physical activity interventions are discussed. This is not an exhaustive review of theoretical models but rather focuses on models most commonly applied to physical activity.