Personally, I think fitness can make people more cheerful, because fitness can make his body more standard and better, and naturally he will be more confident. After he is confident, it is easier for him to carry out some language expression activities and make new friends in some social occasions, which will help to improve his depression.
I used to be a very introverted person, so I can't speak very fluent language. In other words, when chatting with some friends, I may feel helpless and uncomfortable with myself. Then I got a fitness card when I first entered the university. I felt that my body shape needed to be improved than ours, and then I persisted for almost three years and more than two years. I feel that I have made some friends in the gym now and I am more willing to chat with people in real life.
Of course, this is my personal opinion. If you have depression, you should consult a corresponding psychologist. You can't completely let him heal himself, or let him go. You want to get a thorough solution through some other methods. I think these are hidden dangers and unrealistic. Fitness can really improve people's mental state and make them more optimistic and positive. At least when you are exercising, you get in touch with more people. Living alone at home or sleeping quietly or playing games in the dormitory is not good for health and spirit.