Make a list of all the people whose opinions you care about. Close friends, colleagues you work with, parents, whatever’s true for you.
Now, observe your behavior for the next week or so. How much time do you spend interacting with people not on that list? How often are you finding yourself getting upset or into arguments because of people not on that list?
If someone wasn’t on that list, they should have no capacity to anger you. They shouldn’t rile up any strong emotions at all. And you should be spending very little time on activities directed at them.
You have a kingdom, and the citizens of that kingdom are everyone on that list. What happens outside of that kingdom doesn’t concern you – so don’t spend any of your kingdom’s resources on it.
The Opportunity Machine 