Initially, you do not have to be perfect as you write. Just keep writing everything as they flow. Then leave it and return to it for editing. When you try to correct phrases, and sentences as you write, it will slow you down. And you may likely forget those beautiful ideas your brain was generating.

I can relate to this particular one you know.
I'm fond of writing and going back to do some editing. I have so many documents on my doc app where I type so many things down and go back to it later to do some corrections where needed, even though I'm always reluctant to post them.

Did you see the way your voting power works? If you overwork it, it drains, and the value diminishes. The same thing happens with your brain. It is best that you do not wear it out. Give it a break by going for a walk, sitting out, reading a book, exercising, etc. It will make your work seem effortless.

As for my brain! I don't joke with it . I figured out that when I stress it too much I always end up with a headache. So it does deserve a break. But come to think of it! Does the brain really rest at all??
But then, the steps to being a great writer as stated here was really helpful thanks @edystringz.