I think I broke my brain

OK. Turned in a book in October, the sequel is due in March-at-the-latest and I Cannot Focus. On anything. Reading, writing, 'rithmetic -- I can't keep my attention on any of it. Part of this probably has to do with the thyroid slowdown, to which tweakage has been applied, but relief on that front is four-to-six weeks out. I can kind of space most of the non-writing stuff on my plate at the moment; the day-job isn't being particularly disruptive, but -- that deadline ain't gettin' any further away and I have got to get with the program.

I've tried AiC and Just Doing It (which is how the October book got written) -- but my will-to-write seems to have dried up and blown away.

So -- what do you do to get motivated, and stay focused?