There are good things, bad things, and neutral things in this world.
As someone who understands mental health strughles as much as anyone else, you should do is put yourself out there as much as it feels right for you.
Maybe try to talk positively to yourself even if you don't believe it, or think about things you like.
Smiling also releases the "happy chemical" in the brain, so even when it's a fake smile it can eventually improve yoir mood even slightly.