Tell him to do some meditation. Show him some inspirational movies like Forrest Gump, The Shawshank Redemption :)
Yes, as the previous comment states, meditation can do wonders. Indulging in thought decreases awareness, which also decreases your ability to reason. Let him know that if he takes pride in himself, he should also work on increasing his awareness which will make him more controlled, smarter, and emotionally stronger.