Don't despair, it doesn't mean you're a failure. Not everyone succeeds the first time. Many people try several times before they finally quit for good. Each time you try, you can learn something that will help you the next time. So, although you think you've lost the battle, you can still win the war. Prepare yourself, pick a day to stop again and go ahead, make A FRESH START! However, it is best to quit once and stay quit.
Other benefits of giving up smoking