Be the person who sets the tone by their actions, thinking proactively, instead of the person who is reactive to everything around them. The thermostat sets the temperature, while the thermometer tells you what the temperature is and has no influence over it.
Don’t let someone else set the temperature for you. You can only control so much in life, but some of the things you can control are what actions you take, your attitude when you take them, and how you respond to external events. Be more like the thermostat, not the thermometer.