Okay, in Twelve Step programs they have a bit of advice that goes like this: Live in the solution, not the problem. So, what does this have to do with getting the words into the manuscript?
List your reasons for not writing. Go on. We'll wait for you, and here are a few to get you started.
Nobody believes in me.
I just can't get started.
There are too many demands on my time.
I just can't seem to sell a word.
My ideas don't seem to go anywhere.
No support from my family (friends, parents, spouse, partner, bartender, etc.)
Poor health, low energy, can't concentrate, the neighbor's dog keeps barking, my dealer really wants to get paid, it all seems so hopeless.
Here is an example of living in the problem: "Look at what's happening to me; I just can't win! Boo hoo!"
Here is an example of living in the solution: "This is standing in my way; Now, what can I do about it?"
In my own case, I had a destructive childhood, became brain damaged in the Army, had no clue where to begin, and was a full blown alcoholic and prescription drug addict---and that was when I began writing. I did okay. Every problem has some kind of answer, even if it's only to accept the limitation and work within the remaining wiggle room.
A good friend of mine, a professional photographer, lost most of his sight. After a good old wallow in self pity, he wondered what his new view could contribute to his work and went back to taking pictures. A fellow at my "Writing for the brain damaged" talk at Readercon this past July was a composer who lost a good part of his brain in an auto accident. After hearing about my friend the photographer, he decided to try writing music again, curious as to what his new compositions would sound like.
Ninety percent of writing is discipline. That's the part that allows you the thrill of bathing in the wonders of the remaining ten percent. Find and use your wiggle room. If you were able to read and understand this post, you have enough wiggle room left in which to write.