Today I started my day with an old friend, the Leadership Bible (NIV by Sid Buzell and Bill Perkins) which I am sorry to say is now out of print. Having loaned mine to a friend, I had remebered that I had given a copy to my father. I have borrowed it, since it has been untouched since the day that it was given as a gift.
As I opened it, I turned to the table of contents for an appropriate topic, and was immediately drawn to the principle of Purpose/Passion under the personal development perspective of leadership principles. Paul is a person in the Bible that every person who believs in Christianity should know personally. Paul was a man after his own personal development until he was introduced to God, and having endured extreme hardships in his walk with God, is credited as "more than any other single person as being responsible for initiating the spread of the gospel around the world" (Sidwell and Perkins, p.1391).
Leaders must be passionate and affectionately enthusiastic. I would also add charismatic, but there are plenty of examples that anyone can note to the contrary.