“It’s getting late! Don’t you think you should get to bed?” In his youth, it often happened that Kelvin Kwong, nowadays Head of behaviour change at Jawbone, got this demanding question from his father, poking his head into the bedroom. A decade and a half later, not much has changed. '[B]ut what’s different is the nudge', he says, that instead of his father intervening, comes from the data-driven Smart Coach self-tracking system. Drawing on an analysis of online materials, this paper explores how the data collected by the Jawbone UP wristband are given a voice that not only feels personal but also relates to and somehow only makes sense in a particular social and cultural context.