Late adolescence, between the ages of 15 and 19 years, represents a critical stage in life in which young people develop a sense of identity and independence as they transition to adulthood. This stage in life also involves pressures of maturation, academic performance expectations, and changing social roles. Compound these pressures with economic and psychosocial adversity in childhood and early adolescence, including abuse and neglect at home or racial/ethnic, gender, and sexual discrimination, and there emerges an increasing crisis in adolescents' mental health. Worldwide, the prevalence of mental health disorders (eg, depression, anxiety) increases markedly during late adolescence, reaching a peak during early adulthood (ages 20-24 years).Juxtaposed against these trajectories of declining mental health, late adolescence is also marked by decreases in health-enhancing physical activity behavior. The results of a prominent systematic review and pooled analysis revealed that between the ages of 10 and 19 years, this decrease equates to a 7% yearly reduction in physical activity. 1 An increasing body of longitudinal and experimental evidence points to the capacity of regular physical activity to contribute to positive mental health outcomes and buffer against ill health. 2 Previous work suggests that, for many individuals, acute bouts of physical activity can alleviate some of the deleterious emotional effects of experiencing stressful events. 3 In recognition of the benefits of regular physical activity, schools are universally considered to be key settings for providing regular physical activity through curricular (physical education), cocurricular (recess and lunch), and extracurricular (after-school programs and school sports) activities. Within general education systems worldwide, a United Nations report 4 identified that in 97% of countries surveyed, there were legal requirements for or it was a matter of general practice that adolescents receive regular physical education. Nevertheless, even when policy and state laws exist, the reality often involves diminished scheduling and uptake of physical education, especially in the upper secondary levels (ie, late adolescence), with time redirected to other academic subjects (ie, competing pressures of academic performance). 4 Of interest, recent evidence from the United States indicates that although 33.3% of states have minimum requirements for time spent in physical activity in elementary schools, this percentage decreases to 24.5% of states for middle or junior high schools and 9.8% of states for high schools. 5 In short, a nontrivial gap exists in the typical provision of and opportunities for physical activity in late adolescence. Because of the compelling evidence that now exists linking physical activity to improved cognitive function, 2 as well as the capacity for physical activity to reduce VIEWPOINT