I'm not sure if you saw my older posts, but I leash trained Nakita VERY slowly. I bought a harness and left if by her food dish for a couple of days so she would get used to it. Then I put the harness on her for only a few minutes every other day and would play with her and give her treats and praise.

Then I would leave the harness on her for longer periods of time. I always gave her treats and played with her so that she would associate the harness with a positive event. Then after a couple of weeks I attached the leash and would walk around the house with her. Then we eventually went outside.

I cannot emphasize enough that you have to watch your cat and to do the whole process slowly with much praise! If they are anxious or miserable at anytime during the training, the cat will remember the negative so it's important to make the whole process fun.

Not all cats will take to a harness and leash, but many will accept it more easily if they see it connected to a reward (going outside or treats).