Most drugs are only psychologically addictive - or, to put it another way, they become habitual exercise, rather than physical need.
Caffiene rates very highly, as does nicotine - but like XTC said, with the right mind-set, those 'addictions' can be overcome.

Think of it like this.
You're a ciggie smoker, and during your normal day you might smoke 2-3 cigs in an hour.
But, if you went to see a movie (that lasts for an average 2hours these days), I'll bet you don't even think about having a cig until you get out of the theater...then you're like, "Geez, I gotta have a cig, man!"...
It's all in the mind..you are told that you're gonna be addicted by the anti-smoking regime, so you believe it...you believe that if you go for more than an hour without one, you'll probably suffer all kinds of 'coming-down' shit, that your body will start freaking out and stuff............how many people do you know that smoke in their sleep to keep up their nicotine levels?

Anyways, that's my tuppence worth lol