It's not what happens to you, but how you react to it that matters.

Claude Reydellet, engraving by S. Beyssent. Public domain · Wikimedia Commons
Epictetus
Stoic philosopher born a slave in Hierapolis who taught in Nicopolis after gaining freedom. His Discourses were recorded by his student Arrian; lived c. 50–135 CE.
12 quotes
First say to yourself what you would be; and then do what you have to do.
Don't explain your philosophy. Embody it.
There is only one way to happiness and that is to cease worrying about things which are beyond the power of our will.
We cannot choose our external circumstances, but we can always choose how we respond to them.
No man is free who is not master of himself.
Make the best use of what is in your power, and take the rest as it happens.
We have two ears and one mouth so that we can listen twice as much as we speak.
If you want to improve, be content to be thought foolish and stupid.
Circumstances don't make the man, they only reveal him to himself.
He is a wise man who does not grieve for the things which he has not, but rejoices for those which he has.
Freedom is the only worthy goal in life. It is won by disregarding things that lie beyond our control.