Interestingly, among people who have Helicobacter pylori in their stomachs, only a subset develops ulcers. Some people have bacteria, but no ulcer. I don't know if there is a consensus on why this happens, but it is correlated with stress. If you are stressed and have h.pylori, you are more likely to develop an ulcer, compared to h.pylori and no stress.
So the consensus was wrong, but still not a hundred percent wrong.
Source: Why Zebras Don't Get Ulcers, Third Edition http://www.amazon.com/Zebras-Dont-Ulcers-Third-Edition/dp/08...
Quite a fascinating book on stress.
So the first time(s) you use cocaine, you get a high that's incredible. The second time, this effect is about 100 times stronger than usual, so 10 times less strong than the first time.
Then you want to go back to that first unbelievable fantastic time, and take more. You may get at 200, but the more often you take it, the less the effect, and the stronger the craving for it. This is more or less how (this) addiction works.
The numbers I use here may be different, but it shows more or less how it works. Well as far as I understood it from the book Why Zebras don't get Ulcers which is about stress and all its side effects.
http://www.amazon.com/Zebras-Dont-Ulcers-Third-Edition/dp/08...
"Brain Rules" by John Medina [http://amzn.to/UCgCPG] John, a molecular biologist, looks at things such as health and cognitive development and performance of kids and adults from an evolutionary perspective. He highlights problems with our approaches to work and study, how these are at odds with the way our brains evolved to work and what we can do about it. Great collection of actionable advice backed up by current research. See more at http://brainrules.net/
"The world until yesterday" by Jared Diamond http://amzn.to/1AAJjNL Great book on how "traditional" societies handle trade, war and interpersonal conflicts. Lots of thing to consider taking on board in "modern" societies - such as restorative justice.
"The Antidote: Happiness for People Who Can't Stand Positive Thinking" by Oliver Burkeman http://amzn.to/1rITiKX Great overview of pitfalls that "positive thinking" approach brings and how one can start employing alternative ways of attaining happiness.
2. Why Zebras Don't Get Ulcers [ http://amzn.to/1kFszdH ] - great book on stress and its effects by Robert Sapolsky (have you seen his lectures on behavioural biology? Fascinating stuff, even if you always thought 'meh, biology' - the guy is an amazing lecturer)
Basically this guy made his scientific career by doing epic experiments where he observed communities of baboons during various social interactions, blow-gunned individual baboons with tranquilizers, then very quickly, took samples of their blood to analyze glucocorticoids (these are stress-response hormones and have a half-life measured in minutes).
Anyway, crudely stated, the major finding is that animals have intense episodic stress throughout their lives but never suffer health consequences from that stress because it's occasional. Humans, on the other hand, can get the same levels of "fight-or-flight" stress but at long-lived, daily intervals. Excessive glucocorticoids, over a long term, can interfere with the normal functioning of the body and precipitate a wide variety of health problems including heart-disease (and ulcers, as the title suggests).
In the case of driving, an aggressive lane-changing drive in a fast car might be exhilarating under certain conditions, but it's a different story for a daily commute. It's no accident that the advice given to people that experience aggressive drivers on the road is often along the lines of "Let him go, don't become a part of his bad day." Aggressive driving is a self-reinforcing bad habit that becomes part of people's identity in many cases. Personally, I don't care about the health of aggressive drivers, but I do care about their propensity to cause accidents and hurt innocent people.