Visit to the Doctor

I recently selected a new primary care doctor. After two visits and exhaustive lab tests, he said I was doing "fairly well" for my age. A little concerned about that comment, I couldn't resist asking him, "Do you think I'll live to be 80?"
He asked, "Do you smoke tobacco, or drink beer or wine?"
"Oh no," I replied. "I'm not doing drugs, either."
Then he asked, "Do you eat rib-eye steaks and barbecued ribs?"
I said, "No, my former doctor said that all red meat is very unhealthy!"
"Do you spend a lot of time in the sun, playing golf, sailing, hiking, bicycling?"
“No, I don't," I said.
He asked, "Do you gamble, drive fast cars, or have a lot of sex?"
No," I said. "I don't do any of those things."
He looked at me and said, "Then, why do you give a shit?"