A friend of mine wrote me that yesterday in reference to some projects she had in hand. It's not always true, but there is a real nugget of truth in it.
It surely depends on the work, to some extent. But when the work has to be done, it seems like it's better to take care of business than to deal with the ramifications of not doing it.
Whatever the difficulty of a work project that you have already chosen to undertake, if you have chosen to do it and are not seeking some alternative course of action, then to sit down to it and persevere through it's difficulties seems like the only course of action that can hold off the negative self-criticism that often accompanies unfinished business.
One thing about this realization is that, if you're in the pattern of letting fear of work stop you from working, no matter how much you can see the truth of this claim, it's easy to forget it and procrastinate. Fear of work is so much more visceral than this realization that doing the work actually is the most effective way of reducing the fear.