The risks of smoking are clear, and often repeated. But one reason that quitting is so hard is that smoking is pleasurable to smokers. They feel alert, focused and fully engaged in the day once they have had the day's first smoke. Nicotine addiction is strong, especially in those who have started smoking as teens, because the longer they smoke, the more nicotine receptors develop in their body. The behavioral cues that signal smokers to light up are also better established in long-time smokers. Those who quit must overcome nicotine's powerful grip and change their daily routines—sometimes even their friends—in order to succeed. More than 47 million Americans have kicked tobacco, so far. They have worked diligently, with plenty of support, but they have done it.