That man was asking the doctor what he should do to live longer, to which the doctor replied:

"Well, for that you shouldn't smoke"

"I don't smoke at all", the man replied.

"You shouldn't drink"

"I don't drink", the man says.

"You shouldn't eat any fatty meal"

"Oh, I'm very careful with that"

"And you should't do that, um..., you understand, don't you?"

"Well, really, I'd like but I'm living in a forced abstinence"

The doctor finally says:

"Listen! If you don't smoke or drink, you only have fat-free meals, and about other matters we'd better don’t talk, why on earth do you need to live for longer?"