Writing Lessons from the Tennis Court

For the past year, I've been learning to play tennis. And I have learned a lot. Technical, or should I say, technique-al knowledge. Eye on the ball. Drive through your shot. Look for the hole. 
Two days ago, after being away from it for two weeks, I couldn't hit the broad side of a barn. Or, actually, that's about all I could hit - a barn about a mile away. All my shots were high and long. I started to panic. Eye on the ball! Lock your wrist! Swing through your shot! 
My lesson members and teacher were feigning patience.
I became tentative, stopping half-way through my shot, sending the ball even further skyward. Finally my teacher yelled, 'hit it! hard! I don't care if it goes over my head. Just HIT IT!"
So I did. I whacked ball after ball with abandon. And whaddya know, a few of them went in. Burned in, even.
The writing lesson?
Don't get so caught up in all the so-called rules that it ends up ruining your muse.
Learn the rules, yes. But then write with abandon.