Harness training might seem like a lengthy process, but it takes time to help your cat adjust to their latest travel gear. And it is SO worth it. Open your harness with your cat there and test out its features around them. DO NOT attempt to put the harness on right away if your cat is not already harness trained. Leave it out in the open for a few days. When they approach it on their own, reward them with a treat or kisses and play around the harness to form good associations. Once they are familiar with the harness, you can put it on them following this guide. Leave the leash attached inside for a while before leaving the house, so they can get used to the amount of tension from the leash pulling. Keep your first outing short and sweet, like a sniff outside or walk in your yard. Carry them outside so they do not learn to walk out the door.