Take, for instance, studies from the past decade examining the impacts of exercise on daily routines.4.10 When people start habitually exercising, even as infrequently as once a week, they start changing other, unrelated patterns in their lives, often unknowingly. Typically, people who exercise start eating better and becoming more productive at work. They smoke less and show more patience with colleagues and family. They use their credit cards less frequently and say they feel less stressed. Its not completely clear why. But for many people, exercise is a keystone habit that triggers widespread change. Exercise spills over, said James Prochaska, a University of Rhode Island researcher. Theres something about it that makes other good habits easier.

The Power of Habit by Charles Duhigg