I recently purchased a 7 year old mare that has been allowed to do whatever she wants for the past 2 years at least. When previous owner was riding her and Gypsy was done the horse would go to the steps on her own and owner would get off. I don't work this way. I took her outside for a ride and she decided we were done. I said no and lightly slapped her with the end of the rains to go and she started bucking. She has done this while being lunged also. Where do I start to retrain her.