At first glance, a person's pulse might seem harder to monetize than their search history. But that's increasingly false. In his own research, for example, Alter has shown we're more likely to run a marathon when our age ends in a nine—29, 39, 49—because the dawn of a new decade prompts people to seek meaning. "With that knowledge you might advise running shoe companies to advertise to people who are approaching a new decade, or people, more broadly, who might be experiencing life transitions," Atler writes. But if they have a wearable on their wrist, you could directly target only the 29-year-olds clearly training harder than they have before, sending them ads for new sneakers or moisture-wick tops. In the process, you may also discover new patterns that lead to new, data-backed promotional campaigns.