It is never too late to make healthier lifestyle choices.

The health risks of using tobacco and over using alcohol and illicit drugs begin to drop within days after you stop using them. How your past use will affect how long you live or the quality of your life is very difficult to predict. Much of it depends on genetics, which we are just beginning to understand.

If you currently have no damage to your liver or other organs from alcohol or drugs, then it is unlikely you will have problems related to these past behaviors in the future.

Cigarette smoking is not so straightforward. Quitting smoking can reduce your risk of heart disease back to baseline after five years. The risks of chronic lung disease and smoking-related cancers, especially lung cancer, have already gone down since you quit. And your risk will continue to lower with each passing year. However, the increased cancer risk never goes away if a person has smoked regularly for many years.