Have you ever tried giving yourself a pep-talk in the mirror? I do this occasionally, and it really helps me. I think Louise Hay, a new-age self-help author talks a lot about "mirror work."
So here's what happened and what I did: I was obsessing about something that I've been worrying about. So I went up to the mirror, smiled at myself and looked deeply into my eyes and spoke the reassuring words I needed to hear. I did it for just a minute or two. It worked! My mood was instantly lifted.

I think I'll try this more often when I can (not in public restrooms, obviously! Haha!).