Yes! This statement is true. Many sources back this up and all point to one thing, physical activity reduces cortisol levels. According to the National Library of Medicine, "Physical activity decreases cortisol levels, known as the stress hormone, in the bloodstream, alleviating stress and anxiety feelings. Moreover, exercise stimulates endorphin production, brain chemicals that act as natural painkillers and mood elevators." The study goes on to explain how physical activity breaks a repetitive cycle throughout the day and allows individuals to achieve mental clarity. Furthermore, the American Psychological Association also backs this claim up. They state, "Exercise is also good for your mind." Overall, this is a well-supported assertion, backed by both scientific research and anecdotal evidence.