"He who cannot obey himself will be commanded." Friedrich Nietzsche
I came across this quote a while back in the form of a wallpaper. I've been a Nietzsche fan for some time. His works on the origins of morality are the pinnacle of culturally applied logic. My personal favorite is the concept of Master-slave morality. If you aren't familiar with his works on this, it would definitely be worth your time to research.
As for the above quote, I find it to be remarkably paralleled to truths I have discovered in my own life. The word discipline comes to mind. If you do not have the will, the discipline, the mental fortitude to stay true to the rules or goals you set for yourself, then you are bound to be subordinate to someone else. That is how I read into this quote. Nietzsche is calling for some introspection. I will oblige.