If you're at all interested in the science and psychology of motivation, chances are you've read Daniel Pink's bestseller Drive. In it, he argues that three simple things propel us: autonomy (wanting to direct our own lives), mastery (wanting to be good at something), and purpose (wanting to make a difference). Now, Daniel is tackling the art of persuasion in his newest book, To Sell Is Human. We caught up with the author (and Al Gore's former chief speechwriter!) to find out his favorite apps, time-savers, and inspirations.