hmmm a tough one especially when you're going through it. i'm going through the exact same thing now for a long time and honestly there's no one correct way of getting out of it. I feel lucky enough to have found really nice friends around me who check upon me daily so try surrounding yourself with people who really are just nice and happy. highly likely they'd make you feel better!! Also, journaling might help if you're into it? I've recently started writing down all the good and the bad that happens to me at the end of everyday. Helps me calm down a bit (i've got anxiety) and not overthink much about the bad things, because at the end they really are not that big of a deal! also you feel better when you add up and get to see all the tiny good things that happen to you everyday!