Sometimes the pressure of having to work on a dissertation or book is relieved if we work a few minutes a day on another writing project. Call it "Big Project Pressure," where the anxiety and pressure from the "big one" becomes all encompassing, and takes over our lives. You know the feeling, that pervasive, omnipresent force that makes it hard for you to enjoy the little things in your life.
That pressure is so great that we can become immobilized, and avoid it at all cost. It is the 200 pound gorilla (bad metaphor, as gorillas are actually gentle) sleeping in the corner- we are always aware of its power, its ability to destroy our life.
You need to take back your power. As counterintuative as it sounds, start a small second project (perhaps an academic article). Spend 10 minutes a day writing on something else- think of it as your warm up, something to break the daily inertia, and prove to yourself that you can be productive right now. Prove to yourself that you do not have “writer’s block”. The ten minutes spent will not take time away form your dissertation or book, but instead will serve as a means of getting your head "in the game." It will put your dissertation or book into perspective; it is merely a big project that needs to be worked on, nothing more, nothing less.
Remove the stress, begin daily writing on a side project, and then come back to it in a few days. You will be in the “writing groove,” and in a better place to slowly chip away at your project. Oh, and you will have a bit of an article written- nice job!