When it got to the writing-up stage of my PhD (social sciences) I tried to avoid procrastination by setting myself a target of 500 words a day. I figured that if a thesis was 100K words, knocking out 500 a day would get me there in less than a year. I put a few extra rules in place (they needed to be 'good' words, edited, revised and not just enough to hit the word target) but once I hit that target I felt like I had made progress towards the larger goal - even if just a little bit.
Daily targets became sections, sections became chapters, and eventually I had my thesis. Had I not worked to this sort of structure I am sure that I would have put it off one more day, one more week...and never got there even if the research was done.
This is actually how you get anything properly done in regards to your brain chemistry (according to current knowledge). Reaching goalposts consistently propagates the drive to continue.
Daily targets became sections, sections became chapters, and eventually I had my thesis. Had I not worked to this sort of structure I am sure that I would have put it off one more day, one more week...and never got there even if the research was done.