I'm not sure if this strategy is too straightforward to bother mentioning here, but it has made a signficant difference to my productivity in the time since I decided to employ it.

I'm attempting to write up some awkward-to-write-up technical stuff to go in my PhD thesis, and have been putting off getting to the hard part for weeks. About a week ago, I decided on the insanely straightforward hack 'start writing at 10.00 every day, and write until 12.00, during that time, do nothing else'. This has had massive effects. I've written more than I had managed in nearly a month previously - despite that fact that I thought I had spent most of most days attempting to write for the whole of the past month.

I think this is probably related to much of the stuff already posted - it's a less extreme version of Alicorn's suggestion, and it's implied by some of PJEby's earlier writing - it's probably also completely useless to people who have some outside pressure/deadlines which make this sort of 'I really can't even be bothered to start' motivation problem unthinkable, but it is an anti-akrasia tactic that I have been using successfully for at least a short amount of time: tell yourself you're going to do X during a certain time period, and completely ban yourself from doing anything else. Seems silly/obvious, but it appears to work.