My sister is a smoker along with her husband, 2 step children and SIL. However, she doesn't smoke at my house or in my car when we take trips.
We are all going to die of something. As Dennis mentioned, I am overweight. My sister is tiny. Who knows which of us is in better health from our bad habits?
My sister is very considerate about smoking and, even tho I worry about her, I keep my mouth shut. She knows it can be deadly as she is an intelligent woman. Call her dumb for smoking but she is no dumber than people who drink and drive or perhaps even drink too much and don't drive (or overeat or sit in the sun, etc., etc.). As long as her smoking doesn't affect people who don't smoke, she is entitled to her bad habit.
In Ohio we voted to ban smoking in public buildings. Many people just plain ignore it still. They get nasty when you confront them. I would not mind smoking if all smokers were like my sister.
Smoke if you must but be considerate and understand that it could cause you health issues. If you do both, you are smarter than a lot of people out there.