Cats are much safer living indoors, but that doesn't mean they should never get to spend time outdoors. They can derive great enjoyment and mental stimulation from supervised trips outside. One way to broaden your kitty's horizons and enrich her comfortable, if under-stimulating indoor existence, is to train her to walk on a harness and leash. In fact, walking your cat can be an ideal way to allow her safe, controlled access to the great outdoors. Here's a helpful guide for walking your cat.
Via: Dr. Becker on Healthy Pets / Pet MD