Dear Aradia,
My friend's cat lived happily to the age of 21...her name was Hawnie, and she would meditate with us, the three of us...

I would say, just enjoy every day with your special kitty, and at the same time do begin to prepare yourself that within a few years, your friend's health may begin to fail. When that happens, through your love and your special friendship, you will know when the time comes to be with him at the vet for comfort and soothing...it is the last thing we can do for them, and they give us so much.

But, at the same time you never really know; I read once of a cat who lived to be 39 years old (I think it was) and I hope your little friend is with you for a very long time!