Cats, like people, need regular and constant stimulation. While people can flick on a TV and zone out like zombies for a few hours, cats need more demanding mental stimulation. So if you have a cat that’s inside most of the time, consider getting games and toys for your cat.
One popular toy is a wand to wave around your cat’s face so it can practice it’s pouncing skills. Another toy is a puzzle feeder that forces your cat to root out food rather than just munch it out of a bowl. Whatever toy you get your cat, just remember it will probably prefer the cardboard box that it came in instead.