You cannot change what you control, but you can change how you respond to those things. There is a calm that falls over you when you realize this. It fills you with a power that brings peace and tranquility to your mind. You feel stronger in every fiber of your being, but never before have you felt so calm, either.
And what you control is so fundamental, so keystone to your inner peace, that it radiates outward and touches everything that you do. While your realm of immediate, direct control is limited, you are not in a silo. The light inside that you foster builds a grounding around you that spreads outward from person to experience, and back again, flourishing like a crop and nurturing all it touches.
Even more, the things in our control are by nature free, unhindered, and unobstructed, whine those not in our control are weak, slavish, can be hindered, and are not our own.
–Epictetus, Enchiridion, 1.1-2
Your acceptance of what you control and what you don't brings insurmountable stability to your whole being. Build upon this strength, grab onto it and let it elevate you to new ways of being.
Shift your focus and channel your efforts, thoughts, and energy into the things you have control over - especially the way you think about and respond to changes outside your realm of control - only then will you be free.