Winston Churchill said: "There is something about the outside of a horse that is good for the inside of a man." I think that counts for kids too.
He also so said: "No hour of life is wasted that is spent in the saddle." Which is good, because we spend a lot of time there!
When I bestride him, I soar, I am a hawk: he trots the air; the earth sings when he touches it; the basest horn of his hoof is more musical than the pipe of Hermes. ~William Shakespeare, Henry V
"As he was drifting to sleep his thoughts were of horses and of the open country and of horses. Horses still wild on the mesa who'd never seen a man afoot and who knew nothing of him or his life yet in whose souls he would come to reside forever." ~Cormac McCarthy, All the Pretty Horses.