For all our concern of being involved in an accident that will harm us, the odds are really much greater to having poor health that could have been improved by riding a bicycle every day.

Numerous academic studies show that there is a large gap between the average person's guess about the magnitude of a given risk and its true threat...the fact is that even with respect to routine risks that we all run there is generally a huge discrepancy between the true magnitude of a risk and the layperson's perception of it. We're more afraid of shark attacks than heart attacks and statistically that's wrong.

The more awful the manner of death, the more likely we are to be afraid of it, but it leads us to make statistically riskier choices -- to drive instead of fly, to buy guns for personal protection, to take powerful antibiotics when we don't really need them. The flip side of the phenomenon is the whole range of potentially fatal hazards we should be worried about but downplay, like the flu, medical errors, skin cancer and traffic accidents.