If you have the time, you could go volunteer at an animal shelter. This could be sad (if you have to see any put down), but it could be beneficial to both you and the animals. These critters are probably feeling down like you, but having a nice human in their lives, even for a short amount of time, could make all the difference in the world. Even better (if you can/want to)- ADOPT! Then again, if you like kids, you could volunteer in a kids program. I think just finding a distraction so you're not moping would help.
A short walk, even just to look at the trees will give you time to think and should help relieve your stress. I was mad at someone yesterday and after a 30 minute walk (no jogging/moderate pace), I felt calmer and no longer mad.
What are some things you enjoy doing but never have time for? Maybe make the time to do something for yourself. I bet you deserve it and it makes you feel lighter mentally.
Good luck, girlie!