Keeping cats happy inside is simply a matter of creating a healthy and stimulating indoor environment. Some good ideas are giving your cat toys that feel furry or feathery or have catnip inside, providing him with a scratching post at least two feet high, planting pots of indoor greens for him to chew on, adopting another animal to keep him company, and, most importantly, playing games and spending time with your companion. Source: The Humane Society of the United States
Cat Talk: For instance, you can talk to your cat. Some people feel silly speaking to cats, because they think animals can’t understand them. These same people may feel comfortable carrying on long one-sided conversations with infants. Cats do receive information from your conversation: praise, comfort, and a sense of security.
You can get information, too. The more cats are spoken to, the more they will speak back. You will learn a lot from your cat’s wide vocabulary of chirps and meows. You will know when it is time to get up (at least in your cat’s opinion), when your cat is feeling affectionate, or when your cat is feeling critical or threatened, or is in pain. Your cat doesn’t necessarily have something urgent to tell you; a passing meow in the hallway may be a simple hello. Source: Factmonster
Are your cat’s ears twitching in your direction like satellite dishes when you are speaking? He or she is absorbing everything you are saying. Does your cat’s back rise up to meet your hand when you pet him or her? This means your cat is enjoying this contact with you. Does his or her back seem to collapse away under your slightest touch? Your cat is on his or her way somewhere and doesn’t want to be held up, even by a favorite person. Source: Factmonster