Hi we have a lovely 4 year old mare who is great she loves trail ridding and is very sweet but when ever we ride her in the arena she gets mad. She is stubborn unresponsive and pins her ears when you ask her to move out. She does but with a bad attitude. She never does this on the trail so I don't think it's a physical problem. We try to keep the ride interesting to help her but it doesn't seem to help. Also, she is mostly ridden on the trails. What do you think we should do to help her get over this?