You may have heard the Serenity Prayer, made popular at Alcoholics Anonymous meetings: “God, grant me the serenity to accept the things I cannot change, the courage to change the things I can, and the to know the difference.”

Its author, the Christian theologian Reinhold Niebuhr, didn’t come to this insight all on his own. The idea comes from Epictetus, born a slave in 55 AD in Turkey, a pagan.

Epictetus was one of a group of ancient philosophers called the “Stoics,” who also inspired , a science-backed treatment for and as well as . He didn't say we should ask God to grant us serenity, courage and wisdom. He thought serenity and courage came from wisdom. Either way, this piece of wisdom—about knowing the "difference"—is the same.

As a slave, Epictetus by definition wasn’t free in ways that we are. I don't know the details of his early life; still you can imagine that he didn't have our sixteen coffee options at Starbucks. Think the word "slave" and you can see why for him any chance of came from accepting his lot--while also having the huge courage to use any bits of freedom he did have. For a slave, knowing the "difference" was a matter of life and death.

What does that have to do with us? We have vastly more freedoms and more technologies, ways to change things. Yet still, much is out of our hands. Babies cry, no matter what you try. Your first-grader is allergic. Your company is having financial troubles and everyone is tense. Your husband is obese and won't listen when you nag him to lose weight and exercise. Your sister doesn't listen at all. Your mother has and can't listen--and you must watch her deteriorate.

Today, we call people “stoic” when they endure discomfort or tragedy without complaining. But simply being silent isn't the goal. Stoic philosophers advised us to make our peace with discomfort—and so be more content. They understood that babies cry, and other people behave in ways that burden you. The first step to lightening the burden is to see what you can't control. Whenever we focus on things we can’t control, we create tension in our body that contributes to illness and unhappiness. We don't accept what comes our way; we fight battles that can't be won.

Part of the problem is thinking you ought to be comfortable all the time. Sometimes it's harder to see, however, that you're also fantasizing more control than you actually have. If you always blame yourself when things go wrong, you are fantasizing control. It's a hard concept—because you don't feel in control. The giveaway is that you think you should be. The problem is your thinking. You rehearse in your head, or fume inwardly about how you didn't deserve any of this. What makes you think you would always get what you deserve? Do other people get what they deserve? Is the world fair? Always? But you should have been on top of it to prevent this mess!

Your is to manage your response to flux, unfairness, and all that isn't to your liking and see where you can make a difference.

Marcus Aurelius, a Roman emperor, lived in great luxury for his time. It’s easy to be dissatisfied when you’re fortunate, and other emperors were driven to disgusting excess. Just like we can learn from a slave, we can learn from this emperor, who advised maintaining “an attitude of in the present moment for anything that comes your way.”

An emperor was grateful! Well, he had a lot to be grateful for. Still, it's sadly common for people to think wrongly that they earned every bit of their own good fortune and are entitled to it by superiority or birth: "I have it now, so it's mine, forever." The next thought is the that they shouldn't pay a cent in taxes--that it's "smart" not to contribute to the general welfare.

Be clear that any good involved the contributions of other people and circumstances, and goods you enjoy today could dwindle or disappear. Loss is real. Gratitude comes from that. It will also make you happier.

So the Stoics advised us to regularly contemplate losses and be grateful.

Stoicism doesn't imply passivity—just the opposite. The other side of the quote is "the courage to change the things we can." You may have heard the idea, “You can’t control life, only your response to it.” That is a paraphrase of Epictetus, who famously wrote, “We control our opinion, , desire, aversion, and, in a word, everything of our own doing. We don’t control...everything not of our own doing.“

The Stoics focus on controlling thinking and behavior—a concept that evolved into -behavioral . See in the quote above "opinion, choice".....that's cognition, thinking. "Everything of our own doing," that's behavior.

They were on to the need to set priorities and not be distracted. They advise us to consider which and activities sustain us and lead us toward fulfilling our deepest values.

Consider for a moment how your life might improve if you gave up trying to control other people or regretting your lack of control, and took responsibility for your opinions, choices, and actions. Imagine if you didn't blame yourself falsely for losses. Imagine if you were grateful for the little things and focused on what was most important to you. You might be lighter-hearted as well as more deliberate.

It may seem strange that thinkers from so long ago could help us with our modern problems. That strangeness, for me, helps make ancient more effective. Of all the crazy things people have thought in the years between now and 55 AD, some ideas were useful and some were true.

For a fuller discussion of the Stoics read “A Guide to the Good Life: The Ancient Art of Stoic Joy,” by the philosopher William B. Irvine, or The Daily Stoic: 366 Meditations on Wisdom, Perseverance, and the Art of Living, by Ryan Holiday and Stephen Hanselman.

A different version of this piece appears on Your Care Everywhere.