You might of heard of oxytocin — a naturally incurring hormone that's known to lift mood and help deal with stress. (It reduces cortisone, lowers blood pressure, etc.) You can't buy in it pill form, but that doesn't matter because it's easy to raise your levels normally.
Just give someone a hug. Better still, give lots of people hugs. Wrap them in your arms and hold them for a couple of seconds. That's all it takes. Physical contact will send your oxytocin (and your mood) soaring.
Close social contact is a good antidepressant anyway. In a recent study, a large group of depressed women were paired with a volunteer friend and spent an hour a week with them talking. Two-thirds of the depressed woman felt better.
The contact doesn't even have to be with a human, spending time with a pet can have similar results. In a study by the University of Missouri, non-pet owners played with a dog for just a few minutes a day. Blood levels of oxytocin and serotonin (another mood elevator) rose significantly. You don't need to own your own dog. Petting your neighbour's dog seems to work just as well.
Something to chew on.