Sarah Goodyear:

According to the results of a Danish study released late last year, my Dutch friends are giving their daughter a less tangible but more lasting gift along with that bicycle: the ability to concentrate better. The survey looked at nearly 20,000 Danish kids between the ages of 5 and 19. It found that kids who cycled or walked to school, rather than traveling by car or public transportation, performed measurably better on tasks demanding concentration, such as solving puzzles, and that the effects lasted for up to four hours after they got to school.

I’ll bet this link is present in people who bike or walk to work too.