Smokers! The most difficult obstacle you will find is being around other people that smoke, especially friends that "shared" your smoking habit. Smoking is such a social thing that you may even find some of your friendships may have to change a bit too accomodate your healthy benefits. Avoid situations that will be tempting for you and remember how good you will feel when you will be a non-smoker!
PPT. People places things that trigger desire to smoke. Like after dinner cigarette. Like smoking when you're having some beers. Like spending time with people who smoke around you. See your doctor for pharmacological help if necessary. Be resolved and stop this "nasty habit" for a healthier happier life. See http://www.Smokefree.Gov/.