I whinge and moan, and when a well-wisher stops to tell me 'This too shall pass', I latch on to their ear and don't let go for hours. I've never yet got a talker's block. So, ahem, be warned. Don't ask me such questions.
Seriously, I do two other things. I milk the situation by writing about it - http://www.maysuninc.com/articles/wri... – and I work on several projects simultaneously. So if I get stuck on one, I leave it for the moment and move on to another.
Finishing another thing generally gives me the energy and enthusiasm to return to work more effectively on the previous one. Unless, of course, it's a complete dud that needs to be abandoned for the continuing good of humankind.