Background <p>While financial literacy is often linked to economic decision-making, its influence on non-financial behaviors like physical exercise is less understood. This study examines the association between exercise behavior and financial literacy overconfidence and underconfidence. We hypothesize that overconfidence may reduce perceived need for exercise, while underconfidence may lower self-efficacy to engage in it.</p> Methods <p>Data were sourced from the 2009–2010 United States Preference Parameters Study (PPS), comprising 3870 respondents. Financial literacy miscalibration was defined as the discrepancy between objective and subjective financial literacy. Exercise behavior was assessed through self-reported regular physical activity. A probit regression model analyzed the association between financial literacy miscalibration and exercise, controlling for demographic, socioeconomic, and psychological factors.</p> Results <p>Findings partially supported the study hypothesis. Financial underconfidence was significantly and negatively associated with regular exercise participation, suggesting that underconfident individuals are less likely to engage in physical activity. However, financial overconfidence did not show a significant effect. Additionally, financial literacy itself was positively associated with exercise engagement, indicating that individuals with higher financial literacy are more likely to invest in their health through regular exercise.</p> Conclusions <p>These results suggest that the miscalibration of financial literacy, particularly underconfidence, can negatively influence non-financial health behaviors like exercise. Interventions aimed at improving the calibration between perceived and actual financial literacy may have beneficial spillover effects on physical health. Enhancing financial self-awareness could be a novel strategy for promoting healthier lifestyles.</p>