Start With Why is one of those books every leader should have on their bookshelf as a well read resource. In it Simon Sinek helps us focus on the real value of our message by focussing on the most important part of it, the why.
Since I first read the book I have changed the way I communicate elements of the agile development process with my teams and I believe it has improved my effectiveness as an agile coach and leader. I would strongly encourage you, if you haven't already, to grab a copy of the book and digest it well. Sinek draws from great examples including the rise, fall and rise again f Apple and how the 'why' helped them rediscover who they were. But this is one of many great examples he uses so grab the book and learn how a subtle change in your message can reap much richer rewards and help you become a much stronger leader.
The book is available on Amazon UK and Amazon US in multiple formats.
And as an extra treat, here is Sineks presentation at TedXPugetSound from 2009 where he shows us how great leaders inspire action by starting with why.