Do some unexpected kindness for someone close to you... or anyone, really.
Random acts of kindness and spontaneous expressions of love are never a waste of time and always make me feel even better than the person for whom I do them. It's the best antidote I know for my own bad attitude or personal funk.
I'm a total junkie for the response... and am horrible at keeping surprises... so, yea, it's totally a selfish thing for me to make someone else happy. I think it's a good kind of selfish, though. :)
Get out there and pay it forward, Y'all!