There are a whole new range of problems that come with a 'House Cat'! The House Cat is not able to indulge in what comes naturally, and therefore this can create enormous problems mentally and physically!
He/She never gets to hunt and kill and eat naturally and therefore their diet needs to be more extensive than a Cat that has access to outside!
Your home needs to be 'Catified' for a House Cat in order for him to stay happy and healthy!
If you have a 'House Cat' which is often the case in these times of pets being stolen which is fast becoming big business! You have to bring the outside IN, to a certain extent! There are many things that can be done at little or great expense to make their lives much more interesting and enjoyable.
The more activities you can give your cat the happier it will be.
Cats need exercise, especially indoor cats. Check out this video on how to keep them busy.