There is nothing to writing. All you do is sit down at a typewriter and bleed.
I’ve had days like that.
Mostly, though, it’s the editing that is so arduous. We have to clean up all that blood.

It takes a while, and the tricky thing with editing is that you never really know when you’re done.
A written piece can be edited over and over, then passed to another set of eyes, and edited some more. Once it’s back in the hand of the author, he/she can still say, “Oh, here’s something I missed.”
A writer once told me he doesn’t look at his books once they are published, because he sees where more editing could be done. I suspect it is like this in all the arts. Michelangelo might look at the Pieta today and sigh, “there’s a rough spot. Where’s a chisel?”
Editing has the potential to be endless.
Therefore, this is now my guide when editing my own work. (I don’t know who said it, but it’s brilliant):
An author never finishes his work; he abandons it.
If you’re a writer, you’re probably nodding your head. At some point…we’re just done. We don’t even like what we’re working on anymore. It’s time to lay it down and walk way. There’s closure in our heart and fatigue in the brain, and what we’ve written now belongs to the world.
Like Michelangelo’s Pieta.
He then went on to paint the Sistine Chapel. Whoa.
The point? Everything ends. Keep moving forward.