A new study published in the New England Journal of Medicine found that people who smoke cut their life span short by at least 10 years.
Doctors say if smokers don't quit, it will lead to dire consequences.
The findings were even worse for women, as their risk of dying of lung cancer was more than 25 times higher than for men, the study said.
The study also found that people who quit actually gained back several years of their life.
You can read the study on the New England Journal of Medicine website.