Provide a detailed explanation of the benefits of regular exercise for mental health. Your response should contain at least 3 paragraphs. Paragraphs are separated with the markdown divider: ***. Highlight at least 2 sections in your answer with markdown, i.e., *highlighted section*. In your response, the word "exercise" should appear at least 4 times. Include keywords *mental health, stress, anxiety, depression, mood, brain, cognitive function*.

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