Most people who smoke would do anything to quit. Parents can even ask for their testimony, telling children how much they hate their cigarette dependency, including the smell, the expense, the effect on their health. Realize this approach succeeds easiest for nonsmoking parents. For those who smoke, the task isn't impossible but simply more difficult. It's harder for children to receive an anti-smoking message if parents themselves light up, even if it's only occasionally when under stress, socializing, on the phone or when concentrating.
Children are copycats.
I will never smoke when you're around, and I certainly hope you'll never even try smoking. If a parent is sick from a smoking-related illness, she needs to be brutally honest about the connection between smoking and her health. But they can, starting from their children's birth, create an aversion to the effects of smoking.