If you have a videocam, just set it up and let it go. If you just have a tape recorder, that would be great too. Not only will your loved one have a superb walk down memory lane, generations to come will bless you. Don't ever feel guilty for enjoying life. When you find yourself having a great time, and I happen to cross your mind, don't even feel bad for a microsecond.
Life is short.
For all of us, whether we live to be 10 or 105. Enjoy the hell out of it. I would if I were in your shoes. Heck, I do now. But you can only spend it once.