I'm borrowing from FlyLady here, but I'm finding it helpful to think in baby steps...
When I look down my action list and find something I don't want to do, I try to think of a baby step that doesn't make me uncomfortable. Just some small, seemingly insignificant thing I could do. For example, if the task is to write a letter, a small step would be to create an empty letter file in my word processor and save it.
If I use THAT as my next action, I feel silly not just continuing on to write the letter. And if I still feel uncomfortable, maybe the next action is to address the letter.
What I'm finding is that when I complete small things, the big things feel easier.
And then again, sometimes I just have to say "Go do that now!"