Provide a detailed summary of the benefits of regular exercise in maintaining mental health. Your response should contain at least 200 words. Highlight at least 3 sections in your answer with markdown, i.e., *highlighted section*. At the end of your response, please explicitly add a postscript starting with P.S. Include keywords *endorphins, stress reduction, cognitive function* in the response. In your response, the word *exercise* should appear at least 5 times.

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