You feel disoriented, and suddenly find yourself in a large stable. The place is huge and clean, with several stable hands working in varous stalls. Beside you is the Percheron mare, snuffling the horse-hide covering your shoulder, and the pear-shaped equine ear ont eh side of your head.
You remember the description Circe had given, and look down at yourself. Sure enough, you have the glossy black coat of a Percheron instead of human skin, and the huge sexual equipment between your legs is definately that of a stallion.
Your face feels the same, but you can tell your ears are higher and definately not human anymore. You can move them. Also, you find you have a long, flowing horse's tail that you also control.
As you are examining yourself, one of the stable hands comes over. He is a boy about 17 or 18, wearing a loincloth, with shaggy brown hair and coarse features. "Queenie is in heat. You wanna service her, or should I use one of the full stallions?"
He seems to know you. As a matter of fact, you know him. Aaron. He has worked in this stable for five years, since just before you were born! Born from a mare as the bastard child of a cursed human. You appear 19 because you age like a horse, but you have the mentailty and shape of a human. Well, almost. You aren't quite as smart, are you?
Part of you realizes this is Circe's doing - she has created a life for you to match her transformation. It seems easy just to let yourself fall into this new existance. But then you'll spend the rest of your life as a dull-witted stable hand and stud, probably dying of old age in 15 or 20 years.