“He who controls others may be powerful, but be who has mastered himself is mightier still.”
Lau Tzu
The greatest form of strength and power is to control and master oneself. If you are truly in firm control of your mind, thoughts, feelings, emotions, and behaviors, then you are truly indomitable.
Work on mastering yourself by reading, meditating, studying, being amongst nature and your fellow man alike. Realize that you and you alone can truly be master over the self.