<p>Physical behaviors (i.e., sleep, sedentary behavior, and physical activity) are major drivers of physical and mental health. Existing behavior change models (e.g., social-cognitive models, humanistic/organismic models, socioecological models, or dual-process models) only account for a modest proportion of the differences in physical behavior between and within individuals. This limitation may stem from three key shortcomings. First, these models tend to focus either on short-term determinants or long-term consequences. Second, they overlook the bidirectional nature of many of these relationships, where consequences can also function as determinants. Third, physical activity, sedentary behavior, and sleep are intricately interrelated, constrained by the fixed duration of 1440&#xa0;min per day. To overcome these limitations, we introduce the <i>24-hour cognitive-affective physical behavior</i> model. At the center of this model is the 24-hour physical behavior construct, which is embedded within a framework of determinants and consequences, interconnected by eight partially reciprocal pathways that operate on distinct temporal scales. Our model offers a holistic, multi-behavior perspective, shifting away from single-behavior approaches, and introduces clearly defined temporal dimensions to test associations between 24-hour physical behavior compositions and cognitive-affective determinants as well as health consequences. The long-term objective of this framework is to identify the optimal balance of 24-hour physical behaviors that promotes sustained health and longevity.</p>