My watershed moment came on April 15th of this year:

INT-DAY-URGENT CARE CLINIC
GREGORY is sitting on the gurney as the doctor listens to his chest. He is in for a sore throat. No chest problems, no sniffles. Just a fever and a sore throat.
DOCTOR
(concern in his voice)
You smoke?

GREGORY
Well, uh...not anymore. I mean I am a chipper, ya know a social smoker? maybe 5 cigs a day tops. I might do ...

My watershed moment came on April 15th of this year:

INT-DAY-URGENT CARE CLINIC
GREGORY is sitting on the gurney as the doctor listens to his chest. He is in for a sore throat. No chest problems, no sniffles. Just a fever and a sore throat.
DOCTOR
(concern in his voice)
You smoke?

GREGORY
Well, uh...not anymore. I mean I am a chipper, ya know a social smoker? maybe 5 cigs a day tops. I might do that for a couple weeks at a time then not smoke for months, even years. Then pick it up again. You mean you can tell I smoked that little just by listening.

DOCTOR
(smugly)
Well, yeah.

How old are you?

GREGORY
I just turned 40.

DOCTOR
Let me put it this way. At 40 your warranty has run out.

GREGORY
What do you mean?

DOCTOR
Well, with guys up until about 37 you can do stuff to your body and not really suffer the consequences too much. After that, just about everything you do will have a impact on your health.

GREGORY
(a look of shock and dismay crosses his face)
Wow. I better make some radical changes then.

DOCTOR
Yup. You got it. Funny, Guys get that analogy. Women don't, I have to explain it to them differently...