Starting to write a new book is like having to jump into a cold pool. You stand there and you go, "Oh shit." Then you jump, and you go, "OH SHIT, IT'S COLD!!!" Then you get out and you look and you whine, "Do I have to?" And you do. So you jump. Again and again and again. And after a while it doesn't feel so cold anymore, you even start sensing new energy. Elated and proud of yourself, you begin to swim.
Now, if you make it or not to the other end of the pool is a whole another story.