Last spring, Shiri Melumad, a professor at the Wharton School of the University of Pennsylvania, gave a group of 250 people a simple writing assignment: share advice with a friend on how to lead a healthier lifestyle. To come up with tips, some…

Last spring, Shiri Melumad, a professor at the Wharton School of the University of Pennsylvania, gave a group of 250 people a simple writing assignment: share advice with a friend on how to lead a healthier lifestyle. To come up with tips, some…