I keep a running tab of amusing horsie quotes for equestrian team clothing...unfortunately I don't think they'd let you print most of them. Some decent ones:

Ride it like you stole it.
"You either go to the hospital or you get back on! Hospital or on!" -GM (I really like this one for life as a don't give up quote)
Don't be the rider who gallops all night and never sees the horse that is beneath him - Jelaluddin Rumi
Don't be distracted by criticism. Remember the only taste of success some people have is when they take a bite out of you.- George Morris
I also like the one in my sig line.

ETA: Love Jeffery Eugenides' books!