After you have made sure your horse is sound and ready for work, begin with short conditioning sessions at the walk and trot only and mostly in straight lines and soft curves or serpentines for 20 to 30 minutes per day. This will allow your horse to build up his muscles slowly while allowing all of the horse’s muscles, tendons and ligaments to stretch. Asking a horse that is not conditioned properly to perform small, tight turns will put undue stress on under-developed muscles, tendons and ligaments and could cause injury.