Nicholas Bakalar writes in “the Times”:http://www.nytimes.com/2005/08/23/health/nutrition/23walk.html

bq. A Scottish study demonstrates that the walkers are more active during the rest of the day than their peers who arrive by car, bus or train. Why walking to school encourages greater physical activity is not clear, but the authors speculate that a morning walk may stimulate further social interaction and lead to more exercise.

Those physical activity habits, over the course of a lifetime, would help millions of people. Renowned cardiologist Jeremiah Stamler, in a “Times interview with Jane Brody”:http://www.nytimes.com/2005/08/23/science/23conv.html?pagewanted=1, points out that “only about 5 or 6 percent of people 35 and over are [at] low risk” for heart disease.