I just saw this video and it talked about out living your life as a thermometer or a thermostat. A thermometer tells you the temperature in the room and a thermostat sets the temperature in a room. His meaning behind it was as a thermometer your days are good or bad based off of external things and you have no control of yourself and your life and how things go. You never have any true control of happiness or anything for yourself. As a thermostat you set your days and you set your happiness daily to what you want. You are in control of if you have a good day or not and your being emanates to others and they conform to the temperature that you set for yourself and your environment.
I think at times we can fall into both categories and I myself can look back at my past and see where I have been both. So a goal of mine is to be a thermostat as much as possible. Make my way so that no one can dictate my success for me.