The main job of rewriting a story is taking stuff out.

I think this also can apply to non-fiction too though.

The hardest. most difficult part is, of course, sitting down and doing the work, to begin with. 

Overcoming resistance – as Pressfield would say.

But when you go back and look at what you have done, it can be like a puzzle of looking for what does not belong, and maybe adding a clarifying statement now and again. 

I think some would argue that rewriting is when masterpieces are made.

Deletion is also the main task of writing a good email.

“When you write a story, you’re telling yourself the story,” he said. “When you rewrite, your main job is taking out all the things that are not the story.”

-Stephen King, On Writing

You don’t have to be a genius to make genius—you just have to have small moments of brilliance and edit out the boring stuff.