haha this thread is great. i too am having these problems. although Bailey is still to small to go outside but i wanted to prepare him for when we can go on walks.
when i put it on him he trys to escape because he would rather play then be sat down.
once it is finally on him he does a complete 180. he turns into poor lil' me dog. runs around the house on his neck like they do when they just had a bath and then goes to sleep. its the same thing when i put a shirt on him. and when he sees the harness in my hand he lays down to go to sleep almost as if it is a punishment to mellow out.
last night i put his new pretty collor on him while we were sitting on the couch and it was the same drama. he looks up at me like he is about to be murdered and i can help but laugh and love him
i just figured i should do this maybe once a day or a few times a week and get him used to it.