Maak er van meet af aan een goede gewoonte van tegen elke pijnlijke indruk van buitenaf te zeggen: 'Jij bent niet meer dan een indruk! Jij bent heel … - Epictetus

Consider when, on a voyage, your ship is anchored; if you go on shore to get water you may along the way amuse yourself with picking up a shellish, or an onion. However, your thoughts and continual attention ought to be bent towards the ship, waiting for the captain to call on board; you must then immediately leave all these things, otherwise you will be thrown into the ship, bound neck and feet like a sheep. So it is with life. If, instead of an onion or a shellfish, you are given a wife or child, that is fine. But if the captain calls, you must run to the ship, leaving them, and regarding none of them. But if you are old, never go far from the ship: lest, when you are called, you should be unable to come in time.

Whenever externals are more important to you than your own integrity, then be prepared to serve them the remainder of your life.

Don’t demand that things happen as you wish, but wish that they happen as they do happen, and you will go on well.