She divided 84 maids into two groups. With one group, researchers carefully went through each of the tasks they did each day, explaining how many calories those tasks burned. They were informed that the activity already met the surgeon general's definition of an active lifestyle.

The other group was given no information at all.

One month later, Langer and her team returned to take physical measurements of the women and were surprised by what they found. In the group that had been educated, there was a decrease in their systolic blood pressure, weight, and waist-to-hip ratio — and a 10 percent drop in blood pressure.