>>7147748Recognise when you're thinking predictively, "Oh, things will turn out this way or another", "I will never..". Don't try to not think, that won't help, but recognise it when you do. Try to live day by day, and don't try to set your standards too high, or you'll be sorely disappointed and your pessimistic thinking will take over again.
In my battle with depression, I've found that taking up a hobby like playing music can be really constructive. Get a kalimba or something, something you can piddle away on without much thought. It might sound gay but finding ways to soothe yourself can be really effective.
I hope you'll find happiness.