Indifference

Home on Sunday night. My cat, Priscilla, Queen of Desserts, feigned indifference for about an hour. I am being punished for abandonment. My neighbor was alternative cat staff and spoiled her fat self rotten. She got over her mad and now sits comfortable close by....she's too heavy to be a lap-cat. She's my rescue cat whose previous owner passed away and no one would take a 10 year old cat. She's on a diet but roams the hillside and gathers her own "desserts". How do you get a cat to lose weight??? Treadmill? Weight-lifting? Cardio?