Abstract
The persistent gap between health intentions and actual behavior calls into question accounts of physical inactivity that treat it as a uniformly rational and freely chosen preference. This theoretical article draws on a non-systematic narrative synthesis of research on action initiation, individual differences relevant to physical activity, and public health ethics. Action-initiation paradigms show that neural activity can precede reported awareness of simple actions and, in some cases, predict aspects of ensuing choices, but they do not establish that such activity causally determines complex behavior or explains physical activity maintained over time. Evidence from behavioral genetics and developmental research indicates that self-regulatory characteristics and physical activity are partly shaped by heritable and early-life factors. We therefore develop an account of situated agency in which deliberation retains a meaningful role but operates under biological, developmental, and environmental conditions that are unequally distributed. Within this framework, individual and institutional responsibility are complementary, with greater prospective responsibility falling on institutions where they can modify avoidable barriers while preserving individual choice. Success should therefore be assessed not by equalizing individual capacity or increasing average population physical activity alone, but by whether improvements in access, uptake, and sustained participation extend to people facing greater baseline barriers.