Jack Welch, from his book Winning had this to say about authenticity and leadership:
A person cannot make hard decisions, hold unpopular positions, or stand tall for what he believes unless he knows who he is and feels comfortable in his own skin. I am talking about self-confidence and conviction. These traits make a leader bold and decisive, which is absolutely critical in times where you must act quickly, often without complete information. Just as important, authenticity makes a leader likeable, for lack of a better word. Their realness comes across in the way they communicate and reach people on an emotional level. Their words move them; their message touches something inside. When I was at GE, we would occasionally encounter a very successful executive who just could not be promoted to the next level. In the early days, we would struggle with our reasoning. The person demonstrated the right values and made the numbers, but usually his people did not connect with him. What was wrong? Finally, we figured out that these people always had a certain phoniness about them. They pretended to be something they were not — more in control, more upbeat, more savvy than they really were. They didn’t sweat. They didn’t cry. They squirmed in their own skin, playing a role of their own inventing. A leader in times of crisis can’t have an iota of fakeness in him. He has to know himself — and like himself — so that he can be straight with the world, energize followers, and lead with the authority born of authenticity.
The importance of authenticity is rarely stressed while discussing leadership; but true leaders are believed because they have an unshakeable belief in what they are saying themselves. If you don’t really believe it, no one else will either.