You rub just out of where she can reach with her hoof and work your way to that area. When your able to rub in that area without her lifting her leg, then tell her, good girl or whatever you call her and rub her neck and head. All horses like praise. Don't get yourself in a position where you will get kicked. Go thru that several times. She will catch on quick. You will want to be able to brush her belly when she starts to shed. Also every inch of her body. PS: her belly does not hurt. If her belly was hurting, she would be laying down and rolling or some time lay upright on her belly and trying to scoot on her belly.