What is a leader?

As I am trying to prepare to teach others about leadership, I am beginning to question my own leadership abilities. I know others say that I am a good leader but what is that? I prepare diligently for anything I do in my life. I have started two power points about the unit topics I am teaching about, but does that make ma a leader? Planning? I also research topics I am unclear of, is that a leader? I believe these things just make me a good planner and organizer. What about following through on what I say I will do? Again, I don't think this is a leader. I am very concerned that others think I am something I am not.
Now in the mental health community, anyone who goes out and raises above is looked at differently. My fellow consumers you are a hero, and to the professionals you are treated with suspicion. I don't do what I do for recognition or anything, I just want to be the best me I can. Is that a leader?
When I think of leader I think of people like Mahatma Ghandi, Rosa Parks, John F. Kennedy, martin Luther King, Jr., Erial Sharon, President Bush, Susan B. Anthony, etc. I defineatly do not see myself like them. They have changed the world. I am just trying to change me so I can be in the world. Don't get me wrong, I do want to make a difference, but recognition is not what I am in it for. I want to help shape the future of this country...one person at a time.