When you are staring down at your document at 6:07 AM, and berating yourself softly, do this:
Take a deep breath.
Make sure your cursor is in the right place (at the end of the current document).
Imagine what you would like to be writing about, if only you were better at writing already, and had explained everything so the reader would get it, and if only you had all the time in the world to explain this cool thing you want to write.
Have you got a clear picture of the thing that you can’t write about, but would like to?
Now close your eyes.
And let your fingertips fill in that picture.
It doesn’t matter if you explain it perfectly the first time. It doesn’t matter if you can’t tell the reader everything all at once.
Just start in one corner of that scintillating scene, and describe one part of it. Then, maybe the part next to it. And so on, ad infinitum.
And . . . go.