You cannot write books with a critical head. You cannot produce good prose if you are the skeptic, scouring every line for the false note, the exaggeration, the argument that doesn’t persuade.
…
The [editorial] hat and sneer came in handy later — once I’d written the first draft. It was then I needed to slap myself around, give the manuscript a hard time, and I was glad to have been a former editor. But I had learned something I’d never known: No amount of study, or work in the field, could prepare me for facing the page alone.

Marie Arana, in her introduction to
“The Writing Life: Writers on How They Think And Work”