I do, however, know why writing is like riding - horseback riding, that is. Forgive me if I've shown this before, but these are my two horses:
Frostie is my 16-year old mare.
Snoopy is her 9-year old son (gelding).
They are Quarter horses, which is a breed.
Learning to ride is what inspired me to write, so I personally know why writing is like horseback riding.
Everyone thinks it's easy to do.
Anyone who has taken a trail ride thinks that you get in the saddle, kick, and your horse goes. People who watch others ride see nothing but the horse's movements. If you don't know, the assumption is that the horse is a point-and-click critter.
Frostie is very ticklish - we call it being light sided. If you kick her, she will take off at warp speed. Snoopy is dead sided. If you kick him, you might get two or three steps before he ignores you completely, except to reach back and try to bite your foot.
Riding them, or any horse, requires what we call a seat, which is another word for balance. You have to balance your body evenly on their back. There are other rules, too. Lots of other rules. Rules about getting them to respond to pressure from your legs, and how much contact to have with their mouths, and even how to get a balanced ride from them (it's called collection).
Having said all that, you can possibly get on a horse, and kick it, and drag it left and right by the reins, and some horses will put up with all that and you can say you're a horse rider. But no one will look at you on a horse and say, "Wow, how graceful! How elegant! I wish I could do that."
Writing has rules. Spelling rules and grammar rules and rules for punctuation and more. Beyond the mechanical, there are rules for storytelling. Show, don't tell. Don't overdo the descriptions. Adverbs are verboten. "No crazy dialogue tags," she yelped. My favorite is Elmore Leonard's rule to leave out the parts most people skip.
You can ignore most of these rules if you want. You can write stories where everyone's yelping and whimpering every line they say, and you can describe the walk from the sidewalk to the front door in such intimate detail that we know the mating habits of the snail in the garden and he's not even a main character. Don't show us anything. Tell us everything. At the end of this, you can have a book. It might even be a book lots of people buy.
But will it be a book that people re-read because they not only love the story, they love the words you chose? Will they say, "Wow, I wish I could do that"?
In my riding and my writing, it's my constant goal: to be proud of what I accomplish.
Here's a video of my trainer riding Snoopy in a horse show at Burbank. I'll be showing him in Burbank this weekend, which will be fun.
As you watch it, look at how little her hand or body moves. Trust me, she's giving him instructions the entire way around this course.
Great riders and writers make it look easy.