When I was a student--some 19 years of my life, so still more than half--I used to reach a point in the semester when I would start to make calculations. Namely, what would end first--the semester or my grades and academic reputation? Luckily, the semester usually ended first. I'm feeling that way right now with work, except that there's no semester to end. No finals to cap things off. No exit except finishing the damn work.
At a certain point, it can feel as if nothing else will come out of my brain. I'm almost there.