You know - the only thing you can really control at all is yourself. So it can be true that the world sucks, but making yourself suck is not going to do anything except hurt you, yourself.

So regardless of the outside circumstances, the best action is always to work on yourself. Generally speaking that does make you look differently at your circumstances too, so that you might be able to improve your situation with some action but even if those circumstances don’t change you are still better equipped to deal with them.