It depends on your health and state of mind. For example, I have a great aunt that is 90 years old and she walks faster than I do, and is still a little spitfire. But then again I have known people that are in their 60's and act like they are about to kill over. It just depends on the person.
Do you know what a gilf is? Grandma Id like to fuck. I was just wondering if anyone has seen a hot grandma that looks young as hell. I haven't.
To use the term old, I would say 65 years or older. But doesn't it depend on a person's condition, habits & lifestyle?