It's from 2009, but still a great talk (click here).
All about the "golden circle" - the world's simplest idea. Why - How - What?
"People don't buy what you do, they buy why you do it."
Every time we watch this video we learn something new. At the time of this posting, this video on this website has 31,809,453 total views. People continue to watch and learn. Enjoy!