Epictetus:
One should know that it isn’t easy for a person to arrive at a firm judgement unless, day after day, he states and hears the same principles, and at the same time applies them to his life.
Epictetus, Fragments, 16
Read the same books, or at least read about the same ideas. Keep reading. The author subtly rewrote your favorite book since you last read it, so why don’t you see what the book says now?
Talk about these principles with others. (But don’t be a boring monomaniac about it, because that has its own dangers). The easiest way to do this is what you’re doing right now. Write.
Apply these simple principles in your life, daily. The easiest way to do this, today, is to talk to God. If you find yourself in rehearsal about some past event that you wish turned out differently, or maybe some future event where you imagine you can create a result, stop. Wake up. Turn immediately and talk to God instead of yourself.
“He was wrong and I told him so” is a recipe for pain. The rehearsal of events that didn’t happen (and probably will never happen) is where I do this the most. I’m imagining a future where someone is wrong and I can demonstrate how spiritually advanced I am when I correct that person’s error.
That’s at least four mistakes I make: living in the “when and then“, feeling that it is my job in the universe to correct someone, imagining that my correction is necessary to that person’s life, imagining that I am right about the topic (maybe I’m not that spiritually advanced!), and finally that this whole event, whether imaginary or God forbid it actually happens, is good for me. I know for sure that the imaginary event, in its moment, is poisonous for me.
When I’m doing this, snap awake and say “sorry, God, but I was off on some fantasy, but now I’m back”.
Maybe this is one of the meanings of The Prodigal Son.