Epictetus' Handbook on Happiness
Dynamic equivalent by Ray Gen
1. The are some things we can control in life and things that we cannot. Things which we can control include our opinions, pursuits, desires, dislikes, in other words, our own mind. Things of which we have no control include our body, property, reputation, other people, in other words, things outside our mind.
The things which are under your control are free. The things which you cannot control are not free and belong to others. If you are are possessed by things you do not control, then you have put your life and happiness into the hands of others. You will blame others and God for your unhappiness. But if you put your happiness under your own control, then you can find that no one can ever have dominion over you. You will stop blaming others for your unhappiness. You will find the key to your own contentment. You will stop blaming others and find peace. No one would be able to truly hurt you.
If you aim for ultimate happiness, then you cannot worry about the things over which you have no control. These things are beneath you. If you seek happiness along with power and riches, you will find neither and lose both.
The rule for happiness is this: center your contentment on the things which are under your control and don't fret about the things over which you cannot control.