Quitting smoking is hard for at least five reasons..Here is #3 and #4
3. Psychological dependence - Smoking becomes a crutch that smokers use to deal with stress and anxiety. The more a person smokes under these conditions, the less other ways of coping are used. Cigarettes quickly replace the other less harmful coping behaviors that a person would normally use. This often leads to an increase in smoking.
4. Habit - Smoking becomes a habit because it's practiced many times a day. For example, pack-a-day smokers lift cigarettes to their mouth and inhale about 109,500 times a year. Also, smoking is linked by habit to other behaviors such as drinking coffee, work breaks, drinking alcohol, and social situations.