If you let the words or actions of somebody else get a rise out of you, if you let a situation get the best of you, if you can’t control your emotions, you open up the door to be manipulated by others. Whether that’s allowing outside influences to “make” you angry, sad, or even happy, that’s giving away your power.
If someone knows how to push your buttons, they can control you to a certain degree. But if you are able to master your emotions, and to remain calm in the heat of battle, you can control your destiny.