Or when you've finished about 80% of your task, but the remaining 20% might as well be millions of miles away because it's almost impossible to finish anything.

I will actively go and do other people's work for them, just to avoid the remaining 20% of the work I need to do. It isn't even hard work! I could get it done in an hour if I put my mind to it! My brain will simply not turn towards what needs doing!