Introspection and self-reflection can help you identify your current strengths and leadership style, but your current way of thinking about your job and yourself is exactly what is keeping you from stepping up, according to Herminia Ibarra in her book Act Like a Leader, Think Like a Leader. You will need to change your mind-set, and in order to do that you need to start by acting like a leader, and then learn how to think like a leader.
My full review of the book is available at my business book reviews website.