The best thing for me is yoga if I'm sad, running if I'm mad or anxious/stressed. But if I cannot summon the will to do those things, then I:
immerse myself in movies or TV shows on DVD
split a bottle of wine with a good friend
If do the above on top of yoga or running, then I tend to bounce back pretty quickly.
It's important to baby yourself, sometimes.
I like Strawberi's approach.
Might have to try that sometime.
If the problem is more chronic — related to stress or mood shifts due to weather — I go back to taking 5-HTP and maybe some other amino acids again, until things normalize, which is usually within a few weeks. I don't have to do that too often, but it's nice to have as an ace up my sleeve.