What do you do to relax at work when things get heavier and life feels more stressful?

I kinda need ideas 'cus I'm tired and I tend to get grumpy and mad. :(

Not really somethings I do at work but when I'm stressed out I just stop working for 15 to 20 minutes and play piano.

The fact of leaving the screen for few minutes help me a lot. And in the worst cases (e.g. long running bug), I try to go out, take some fresh air, see some friends. Sometimes I don't even touch my pc for 2-3 days and after that I feel better.