What do you do? I start praying. I know that sounds like a very pastoral kind of answer. But that's what I am, that and I find that God is the only one who I can verbalize all my stupid rationalizations, he listens and after verbalizing them to him I realize how dumb I'm being.
I start to sense some the things that are good in my life; certainly there are things I need to work on, but I am loved, by a few people and by God.
Now what remains is to keep moving forward, even though you feel like the world has chewed on you a bit.
(For what it's worth this photo very narrowly won a simple Facebook photo contest)