(I'm cross posting this on the Training forum) My oldest Boxer, Trooper Thorn (6 yrs old), is going to be getting knee surgery next week, and will require up to 4 months of rest and relaxation - absolutely minimal walking. We'll have to keep him crated whenever we're not with him, and keep him laying down at our feet when we are. He's a good dog, and won't argue with us too much, but I know this is going to be mentally very tough on him, especially with his brother BeBop still being fully active. We work on tricks and cues every day right now. Does anybody have any advice on good low-physical tricks we can work on to keep him mentally engaged without getting too physical?