Sex only burns about 21 calories, according to new university study

[Malthus]

Take smoking for example - quitting smoking is extremely "easy" physically - you just stop doing it. No-one claims that some mysterious physiological force over which they have no control *makes* them smoke. But of course, actually quitting isn't easy at all.

I thought what made nicotine so nasty was the intense physical addiction it created that is not just psychological, but the result of real physiological processes.

You thought wrong. The purely phyisical symptoms of nicotine withdrawal are mild and disappear completely after a couple of weeks or so if one goes cold turkey. What makes smoking so hard to shake is the psychological aspects of addiction.

http://www.quitsmokingstartnow.com/ArticleSideEffectsOfQuitingSmoking.asp

This is why so many people cycle through quitting and going back to smoking.

This link suggests more long lasting and deeper effects:

http://www.bbc.co.uk/health/emotional_health/addictions/nicotine.shtml

To the extent that it is claiming physical withdrawal symptoms last mnore than a couple of weeks, it is wrong.

Check other sources. Nearly all of them say otherwise. The real problem with cigarettes is not physical withdrawal, but psychological dependancy (which is extremely severe and hard to shake).

Nicotine use can have many different effects on body functions, both positive and negative. Nicotine acts as both a stimulant and depressant on your body. The use of nicotine:

•Decreases the appetite (for this reason, the fear of weight gain affects some people's willingness to stop smoking).
•Boosts mood and may even relieve minor depression. Many people will feel a sense of well-being.
•Raises the blood level of blood sugar (glucose) and increases insulin production.
•Increases bowel activity, saliva, and phlegm.
•Increases heart rate by around 10 to 20 beats per minute.
•Increases blood pressure by 5 to 10 mmHg (because it tightens the blood vessels).
•May cause sweating, nausea, and diarrhea.
•Stimulates memory and alertness. People who use tobacco often depend on it to help them accomplish certain tasks and perform well.

Symptoms of nicotine withdrawal generally start within 2 - 3 hours after the last tobacco use, and will peak about 2 - 3 days later. Symptoms may be severe, depending on how long you smoked and how many cigarettes you smoked each day. Common symptoms include:

•An intense craving for nicotine
•Anxiety, tension, restlessness, frustration, or impatience
•Difficulty concentrating
•Drowsiness or trouble sleeping, as well as bad dreams and nightmares
•Headaches
•Increased appetite and weight gain
•Irritability or depression

Nicotine withdrawal is short-lived and symptoms pass in time, usually in less than a week. Withdrawal is the most uncomfortable part of quitting, but the real challenge is beating long-term cravings and staying away from tobacco.

http://www.nlm.nih.gov/medlineplus/ency/article/000953.htm