stall walking

Question
we have a horse that will walk in circles in his stall. Not just a little bit, but quite often.  How can we break him of this?

Answer
To be honest, I'm not sure. I don't think it will be easy. Try providing toys and hay to distract him. My mare did that and it was because she was bored. I put toys in her stall and gave her extra hay and put another horse next to her and she was fine and quit.