The dissertation is a big deal in terms of the work involved and just its sheer psychological import. Not surprisingly, most folks working on their dissertation at one point or the other face a wee bit of writer’s block.
Its OK. Its normal.
1) Bird by Bird–write a little bit every day.
2) Shitty first drafts–perfectionism is a killer. Get the ideas down, then polish the logic and language.
3) Use visits to your adivsor as a motivation. Verrry clever. If you give her regular opportunities to say “How’s the writing goin?” this may focus the mind wonderfully.
4) 24 hour buddies–the dissertation version–in the same way that setting up a runner’s date will get you out expending calories, setting up a regular opportunity to proof other’s work can act the same way. And nothing makes for a tighter cohort of friends than those who slaved to finish together.
5) 45 minutes on, 15 minutes off–on those days when it is really hard, give yourself chunks of time to laze between writing bouts. Better yet, get in the habit of scheduling full or half day breaks. Some procrastination can be simple exhaustion. Writing, after all, is physically demanding work.