1. Smoking Has Become A Habit: Habits are hard to break. For many people who have smoked cigarettes for a long period of time, it simply becomes a habit. People typically hold on to habits, even bad ones, because they provide a level of comfort.

2. Stress: Some people grab a cigarette when they are stressed. When they quit smoking, they don't believe that they will be able to deal with the stressors of life without cigarettes and thus relapse because the time when one attempts to stop smoking is a stressful one.

3. Weight Gain: Some people are reluctant to give up smoking because they are afraid that they will gain weight. However, there are many better and more healthful ways to lose weight.

4. Chemical Addiction: If an individual has smoked for a long time, there will be some residual affects that make relapsing very easy. While nicotine generally leaves the body in about 100 hours, long term cigarette use affects the brain as well and will require more time to get out of one's system.

5. Lack of Will Power: Some people simply lack will power. They are unable to give up smoking, because they haven't yet developed the discipline and will power necessary to stop.

6. Not Ready: Some individuals are simply not ready to stop smoking. They may well understand the dangers of smoking, but may be undecided on whether or not they want to quit. Pressure from family or friends may spur them to try to quit. However, in these cases, a relapse is inevitable and probably only a matter of time.

Many people are surprised when smokers relapse. They don't understand why people just can't stop. This is due to several reasons. They include a lack of will power, an individual simply not being ready, the chemical addictiveness of cigarettes, fear of weight gain, stress and simply habit. If these factors are not addressed, individuals will likely relapse and start smoking again.