Maybe 68.
It doesn't sound old, but I have seen a lot of famous people die way younger than that, and people where I live, so I reckon if I get to 68 you'll be lucky.
Rik Mayall was only 56 when he died, so that means I could have only 21 years left.
They say the average dying age is 79, but that's very hard to get to that age, what with cancer, heart disease, or even the risk of an accident.