I read online that smokers who quit before they turn 40 can expect to live nearly as long as those who have never smoked. Is this true?"

Two in three long-term smokers in Australia die prematurely from a smoking-caused illness, so quitting smoking at any age is good for your health. As soon as you stop smoking, your body begins to repair itself. For most people, quitting before the age of 35 enables the body to recover from the harms of smoking, though this can depend on genetic susceptibility to the harms of tobacco smoke. 

Smoking affects almost every organ in the body, particularly the lungs and heart. Research published in 2004 (Doll & Peto) found that a smoker loses an average of three months of their life for every year they delay quitting after age 35, or in other words a year of life expectancy lost for every four years of smoking. Of course, not taking up smoking in the first place is even better. People who begin smoking casually can soon become heavily addicted. Quitting can be difficult but Quitline can help you through the journey.