I'm with you. I go through the same cycles, and have been for years. I could list hundreds, no thousands, of memories I have of actions that I regret. All that makes me think that I deserve what I get. You get out of life what you put into it etc. That has to be bullcrap though based upon some people I've met.

If by giving up, you mean isolating yourself or letting yourself be depressed, then that happens to all of us. If by giving up you mean really giving up, then try to follow the advice given above by adam and pierro. Try to just read about others. That helps me sometimes. So does helping others.