I have a tape on "100 ways to Motivate Yourself".
Some of the best I use is "Be Slow to Start With". In other words, just tell yourself that you are only going to spend 5 to 15 minutes on said Yuck project and then quit after 15 minutes. However, you may often find that just getting started will keep you going longer. If you find yourself motivated to keep going, then do so. But if you still feel Yuck after 15 minutes, stay true to yourself and quit.
Actually that's the only one I use regularly. Heh! But it's gotten me over the hump quite often.