Lifehacker has a suggestion for – wait, I’m forever telling you about good-to-great Lifehacker articles, have you bookmarked that site yet? – one way to cope when you’re drowning:
Try it. I have my own systems and they are in my book, The Blank Screen (US link, UK link). Mind you, I think this business of coping on bad days is so important and I believe what I can tell you about it is potentially so useful, I give away that Blank Screen chapter for free. Here it is: Bad Days from The Blank Screen.
I hope it and the Lifehacker article are useful to you.