Coffee. Lots of coffee.

But seriously, when I was a grad student (in science, so it's really more like a job), in less-busy times I could keep my work week down to 6 days a week, 60 hours or so, but in early years and in the final push, it was 7 days a week, up to 80 hours or so. On a bad therapy day, it was really, really hard. Even on a good therapy day it could be hard to stop thinking about it and focus on work.

Compartmentalization, as TTGB said, is pretty key. For me, the way to do that sometimes was to schedule my day down to 15 minute segments. If my mind was wandering, I'd say, ok, it's 1:15 now -- I will think about this, journal about it, whatever, until 1:30, and then I am going to get up and do X task. It helps to actually physically get up and move to another location to do what you need to do, too. Schedule it in as a "break" period, then keep going. Don't fight too hard against it, but also put a limit on it.

And make sure you talk to other people. I find that having to pretend I'm ok with other people kind of tricks me into feeling ok, and if I can ride that ok-feeling to get some work done it helps.

I'm not in grad school anymore, but I still work full time. I have a humane boss, so although it's no 9 to 5, it's manageable. It's very hard, though... by the end of the day, I'm exhausted, and I wish I could tell the other people around me that my day started nearly 2 hours before I even came in!

Good luck with your thesis, critterlady! I was going through a horrible time in T while I was writing, probably the worst period we'd ever gone through. Since writing is so unrestricted, there were some days where I just went home and cried for hours before I could get myself up and working again. But I still did it (one of my committee members liked it so much she asked to keep it!), and you'll do it too, and it'll be great. It does often feel like trying to empty the ocean with a spoon, though.