Best age to stop smoking is before 40 ,In fact do not start all
Only by using strong will power and avoiding all situations where you feel like smoking, chewing tobacco/ or drugs or drinking or using drugs/ weed, avoiding friends who smoke and diverting mind by reading or chewing a gum, like NICORETTE and taking a walk when you crave for a smoke can all help. You can chew Nicorette gum which is nicotine replacement. There are medicines available. Which can be prescribed if asked personally.