Figure "8" cat harness made of 3/8" wide nylon webbing in many colors

Attempting to have your cat walk outside with a harness and leash can be an exasperating experience.  Usually, cats, after having the harness put on them will just lie down on the floor and not move.  Putting the leash on and trying to encourage the cat to move may prove to be useless.  After you put the harness on the cat and it refuses to move, just leave the room and leave the cat where it is.  After a while the cat will move a little bit and may just lie down again.  Don't give up or give in.  If you leave the cat there long enough, it will lose its fear and get up a move around.  When you first put the leash on the cat's harness, the cat may go into the I'm afraid to move mode again.  Just be patient.  When the cat decides to move it will drag the leash around behind it.  When you pick up the leash the cat may lie down again.  Don't worry.  It will eventually come around.