Many Americans became less physically active in the initial months of the COVID-19 pandemic, with one study finding “corresponding declines in mental health for people who exercised less.” Here, Marina Krakovsky asks, “What is it about human nature that pulls people to the chair or the couch when they’d be better off moving on their feet?” Focusing on evolutionary adaptations related to endurance training, she then explains why, "like the sweet tooth at a time when calories are abundant, the need for much more physical activity than many people get is an evolutionary mismatch between human physiology and the present environment."