In the past few years, a number of companies have marketed wearable devices and mobile apps that can track our personal health data. These “mHealth” devices and apps have led to the birth of what is known as the “quantified self” — a phenomenon where individuals start tracking their behavioral, physiological, biological, and other kinds of health markers. A key question of interest in this ecosystem remained unanswered up until recently: Is there any scientific evidence that consumer adoption and usage of these wearable devices and mobile health apps actually leads to a tangible change in their behavior, which, in turn, can show up in concrete health care outcomes? This is the question my coauthors and I investigated in a recently published paper.