I need a detailed response about 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*. Your entire response should be in English, and in all lowercase letters. no capital letters are allowed. include keywords *endorphins, stress, anxiety, depression, cognitive function, mood, sleep*. in your response, the word *exercise* should appear at least 5 times.
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