Smother your yard with srartegic (entrance door for example)piles of catnip and your fat hardy will stay home. Feed churry or catto tubes by leaving it in front of your outdoor cat  (on fence, on plants, on rocks or on patio etc) while you talk to him or her and maybe even pet him or her. You are teaching your cats that I learning to be safer outside to stick to your yard for safety and food. Of course, that may atract other naimals or foreign cats...be prepared.