I've known people who were particularly susceptible to the addictive qualities of tobacco, to the extent that smoking had practically become hard wired into the brain. These were not weak or lazy people, they just become so full of unease from not smoking that they had to start again, just to stay sane. And this is days or weeks after the nicotine has left their systems.

It's gotta be one of the worst addictions out there, but if people want to do it, more power to 'em, I kinda like the smell.