One of my cats loves this little mouse toy that you can put catnip into. It's the only thing I've seen this otherwise sedentary cat play with... but the other 5 cats I've tried this with (not all mine; not that crazy) didn't really care for it.
My mom has harnessed her cat since he was a kitten. He doesn't go on walks like a dog, at all. But she attaches a thick string to the harness and lets him wander around the yard when she's around. He likes exploring like this, and gets hilariously tangled every few minutes. But uhm... you can tell he still hates the harness. Find it uncomfortable and unnatural, I guess. And he was raised with it. So your kitty may not take to one, but it's worth a shot!
Music of the day/week/month/whatever:
The Bird and the Bees - Love Letter to Japan https://www.youtube.com/watch?v=TWYoIoqJURA