I’m pretty sure that when you read the word “patient” in the headline of this article, your first thought was about sick rather than healthy people. A patient in the healthcare sector, however, is like a consumer in the retail sector — both healthy and sick patients purchase goods and services. A healthy patient is the desired goal of doctors. Elizabeth Dwoskin and Joseph Walker report that doctors are studying the use of wearable devices to determine whether monitoring patient activity can help make patients healthier.