Some of you may have read the recent study that tracked people in Pittsburgh on a weight-loss program. In this widely reported study, half the participants were randomly given a fitness tracker, while the other half were asked to record their habits on a website every night. The surprising result was that over a period of two years, the group with fitness trackers lost 8 lbs on average while the group without the monitors lost 13 lbs.

The problem in achieving difficult, long-term goals, such as saving money for retirement or losing weight, is that in order to . . .