This is likely easier said that done but try your best to switch perspectives work on muscle gain trust me you'll feel really amazing once you see results plus you'll need to be taking in protein to gain muscle if you have the option to join a sport work on improving being your best at the sport or somthing gym could be an good if your focus is on muscle gain rather than cardio building muscle or getting good at sports all requires keeping a nutured body while improving confidence in yourself trust me man what youre going through ive been through very similar it's a dark place to be in working on building your body will give you same results in a healthy way best of luck