Push yourself past your comfort zone.
At some point, you are going to say to yourself, "I've never done this before" or "I don't know what I'm doing."
Don't quit.
To become a great leader, you must be comfortable with things going wrong sometimes because everything will not go according to plan all the time. Therefore, to become one of the greats of leadership, you must get comfortable with being uncomfortable to continue your growth towards great leadership.
A statement I believe in. People not only opportunities available to them, but that they find what they are capable of in these situations. Change is constant, therefore always putting us in uncomfortable situations. The only issue is being able to make the necessary sacrifices.