A guy goes to the doctor on his 70th birthday for a checkup.

Doctor:  You're in pretty good shape for 70.
Patient:  Well, you think I'll live to be 100?
Doc:  That depends.

Do you smoke?
No.
Do you drink?
No.
Do you eat a lot of rich, fatty foods?
No.
Do you get excessive exposure to the sun, like from fishing, sailing, or golfing?
No.
Engage in high-risk activities like motorcycling, SCUBA diving, or skydiving?
No.
Do you engage in high-risk sexual behaviors, like frequent casual sex, or multiple partners?
No...

Doc:  So, why do you give a $hit whether you live to be 100???

.