[Wicket]

I think the harness itself represents being in a calm state of being. Like the oppose of a dog getting excite and crazy when the harness/collar is put on, it is because the tools represent excitement and a chance to go outside. It is how the activity is structured and the dog is going to reflect that. If your walks and activities when he has the harness on has a no nonsense structure (no pulling, barking, bouncing, etc), the dog is rewarded for being calm with the walk/activity. On the other hand, if the dog is allowed to be hyper and crazed during walks, the dog is rewarded for pulling its owner around with the continuation of the walk/activity. I don't think it's wrong to leave the harness on the dog, some owners leave their dog's collar on all the time, but it probably would be a good idea to try to teach your dog to be more calm in the house and not just with the harness on. However, if the harness chaffs and stuff, not a good idea. Does your dog get enough mental and physical exercise? Perhaps that's the reason why he's more energetic with the harness off. Or maybe you just need to set the rules with the harness being off as well? Your dog could be thinking, if the harness is off it's time to be excited and playful. It might be a good idea to set aside some special time for him to be excited and playful in a structured manner, and when the time is up he has to be calm and well-behaved.