When are humans most happy? To gather data on this question, Matt Killingsworth built an app, Track Your Happiness, that let people report their feelings in real time. Among the surprising results: We're often happiest when we're lost in the moment. And the flip side: The more our mind wanders, the less happy we can be. (Filmed at TEDxCambridge.) TEDTalks is a daily video podcast of the best talks and performances from the TED Conference, where the world's leading thinkers and doers give the talk of their lives in 18 minutes (or less). Look for talks on Technology, Entertainment and Design -- plus science, business, global issues, the arts and much more. Find closed captions and translated subtitles in many languages at www.ted.com/translate Follow TED news on Twitter: www.twitter.com/tednews Like TED on Facebook: www.facebook.com/TED Subscribe to our channel: www.youtube.com/user/TEDtalksDirector