When I meet Chris Dancy, I ask him how he’s feeling. He grins mischievously and says, “I feel great, and I have the data to prove it!” Over the next 30 minutes, he gives me no reason to doubt the truth of his assessment. Dancy, is at the sharp end of the Quantified-Self movement, which has now blossomed, into a global force. Combining wearable sensors and wearable computers, with self-tracking and data visualisation software, quantified-self(er’s) seek actionable insights into both lifestyle and behaviour. There are now hundreds of meet-ups, happening every week on all six continents.