The Let Them Theory by author and podcaster Mel Robbins may be the latest viral self-help craze that people discount as “pop” psychology. But the “let them” theory actually offers a powerful tool for the therapist’s toolbox and a potentially powerful guide to achieving inner peace. Simple on the surface but rooted in age-old wisdom, the ability to “let them” frees people from unnecessary suffering. But letting go of what we can’t control is not easy. “Let them” requires us to rise above natural feelings like jealousy, envy, anger, and the need to control others. Needless to say, reaching the “let them” state of mind requires discipline, practice, and mindfulness. Reading the book carefully, and even more than once, can provide guidance toward a peaceful state of mind if the reader is open to it.

If someone has a nicer car or house then you do, then “let them,” Robbins advises. Instead of dwelling on what others have and we don’t and feeling envy, the theory advises us to think about what is important and meaningful in our own lives. Here are some of Robbins’s examples: If a friend betrays you, rather than being eaten up by feelings of sadness and anger, the healthier attitude is to “let them.” Then empower yourself by being open to new friends who elevate you and bring out your best nature. Instead of feeling needy and demanding when your spouse is away on a business trip, tell yourself, “Let them,” and pursue what gives meaning to your own life.

Robbins calls the second part of the “Let them” theory “Let me.” Rather than dwelling on external events that cause us pain, the “let me” part of the theory leads us to empower ourselves. For example, in a therapy session Elliot explained that he felt anxiety when his wife Alice traveled for business or when she went on an occasional girls’ weekend. He was angry at her if she didn’t call or text him several times a day. Alice explained that she was always busy on her trips. She didn’t always have the privacy for a phone call or even a text more than once a day in the evening. Elliot was retired and didn’t have enough to fill the void in his life. In therapy, we discussed the need to fill the void with things other than his wife. Over the weeks, Elliot joined a hiking group and a pickleball group. He also started volunteering twice a week with a green energy group. Filling his days with activities that he enjoyed allowed him freedom from anxiety when Alice was travelling. Finally, he was able to “let her.” If a daily phone call was all that Alice could manage when she was away, then he was content with that.

The wisdom of the “Let them” theory is ancient in origin. It is the essence of a school of philosophy called Stoicism, which flourished in ancient Greece and Rome two thousand years ago. The wisdom of letting go of what is not in our control was articulated by a disabled Greek slave in Rome named Epictetus. Although a slave, Epictetus was allowed to study philosophy and later became known as one of the great Stoic philosophers. There is only one way to achieve happiness, taught Epictetus: Let go of things that are not in our control. What is in our control us is our ability to adjust our attitude toward external things. As a slave, Epictetus had little control over external events and other people’s actions in the material world. But he had a powerful mind, which empowered him to adjust his thoughts and attitude in the spiritual, psychological, and mental realms.

Stoicism is often thought of as a philosophy of detachment from the world. In fact, Stoicism teaches detachment from our reactions to external things that cause us anxiety and unhappiness. Stoicism taught that it is not external reality that causes anxiety and unhappiness. Rather, it is our mental attitude or thoughts about the external world. We cannot change external reality but we can change our ways of thinking about it and attain peace of mind. For the Stoics, happiness did not reside in the ownership of material things or achieving a powerful position. Instead, they taught, happiness is a state of inner peace.