Ted Williams - "The Kid", "The Splendid Splinter", "Teddy Ballgame", "The Thumper", "Mr Red Sox", "Toothpick Ted" and "The Greatest Hitter Who Ever Lived" - said that.
He meant it as advice to someone trying to hit a baseball with a bat - arguably the single most difficult thing to do in any sport. Consider that someone who manages to get a hit in baseball three times out of every ten tries is a great success. Only on the rarest of occasions, and not since 1941 (70 years ago), does anyone consistently get a hit four times out of ten. (Oh yeah, and that guy was Ted Williams.)
But as much as I love baseball, this blog isn't about that. What Mr. Williams had to say about hitting a ball with a bat is applicable to all sorts of things, including writing.
Maybe I can press the point with another quote and a video clip. Bruce Lee, in Enter the Dragon, says and demonstrates much the same idea. The quote is: "Don't think; feel. It's like a finger pointing away to the moon. Don't concentrate on the finger, or you will miss all that heavenly glory."
Okay, so maybe that just confuses matters and maybe this whole point I'm trying to make is a stretch anyhow. But the point is that one of the greatest enemies of any writer is over-thinking, over-working, over-tweaking, over-fiddling, over-worrying, over-you-name-it. (Batters, too.)
Once you've put together the basics of something then just do it, and do it some more and even more. An athlete relies on muscle memory to get them through the mechanics of what they need to do. And that only happens through repetition, practice, over and over and boringly over again until you don't need to think about it, you just do it because it's natural.
Writing's no different. The more you do it, the less you have to think about it and the more likely it is you'll find yourself swinging for the fences or reaching out to all that heavenly glory.