I know what you mean by "just lying there" as that's what my cats did at first, as well. It took them a while to get used to the jackets, then there was no stopping them.

I'm glad that you found something that works well for both you and your cat(s) and hope that you both have many happy hours walking your cat. Another fun thing is a cat stroller. Two of my four cats love to go for a ride in the stroller.