One of the hardest things for leaders to understand is that your knowledge is not the backbone of your leadership strength.
It is your ability to meet new challenges positively head-on and goes trust you will learn and grow with them that is your leadership strength.
I find leaders typically believe they have arrived when they hit a certain level. The truth is that each new leadership level requires you to create a new mental picture of who you will be in that role and then build the pathways to do it.
Stretch yourself and never ever rest on your laurels.