Drive
A while back I read Dan Pink's book Drive: The Surprising Truth About What Motivates Us, suggesting that typical opinions about what drives people to achieve are wrong. Essentially he argues that the use of carrots and sticks to attempt to drive people to complete tasks are less effective than intrinsic motivation - finding the achievement gained from completing the work itself to be sufficient to drive a person forward. The clip above is a brief, 11-minute summary of the book.