Break it up into the smallest chunks that you can, write a list of the ones in front of you, then pick one of them. Just start it, do something. Let yourself do just one small task. Sometimes I start by writing junk, just remember to delete it!!! Often once you start you will keep going, if not, give yourself a short break or reward then try to do another small task. Keep on going, keep on rewarding yourself. You can do it.
JUST ONE LITTLE THING AT A TIME, DO SOMETHING and IT DOESN"T HAVE TO BE PERFECT (this is what I have on my white board along with my list of things to do...) Breaks over, I'm back to work now