If you're a vegetarian, and if you hear people talking about a chicken dish being better than a vegetable dish that you cherish, it makes no difference to you. 

If you're a teetotaller, and if you hear people talking about a scotch being better than a smoothie that you cherish, it makes no difference to you.

By defining the rules of your game, as being a vegetarian or a teetotaller, you are immune to comparisons of what you like or have versus what you could be having, when those comparisons are outside your rules.

An extension, then, is to have more such rules defined for ourselves in other domains too, where we would like to immunise ourselves to comparisons. Comparisons about money, titles, material wealth, anything really.

Just like a vegetarian finds it ludicrous to be unhappy about someone else having more chicken than her, by defining the right rules for us, we will find it ludicrous to be unhappy about someone else having more money, a better title or anything else really.

The simple rule is to define our own rules of the game.