This talk by Simon Sinek is one of the best things I've seen on TED. I love it because it intellectualises why I do what I do. The speaker celebrates what I recognise as my inner dialogue and it is doubly inspiring to hear it articulated so well.
Although I'm an avid fan of TED, I first saw this talk posted on Maria Killam's outstanding blog Colour Me Happy. You really ought to have a look; the lady knows her business.