Have you read "Candide"? Voltaire wrote it as a satire on certain overly optimistic and positive philosophical views. It's really short, and I thought it held up great despite the age and translation. Douglas Adams' "Hitchikers guide" series is another satire I can't recommend enough.

Life is as strange, terrifying experience that is often absurdly unfair for no good reason at all. But it can also be kind of hilarious for the exact same terrible reasons.

Develop your ability to see the humor in deeply dark and unfair situations. They aren't going anywhere. You could try to convince yourself they aren't there or that they aren't so bad with some religions/philosophies, or maybe you'll convince yourself that you'll triumph in the end - but most likely you will just end up angry, resentful, and not particularly well-liked as a result. Humor though... that's something other people (and you) can work with.