In 1992 the psychologists Henry Cloud and John Townsend published Boundaries: When to Say Yes, How to Say No to Take Control of Your Life. The publisher calls it a plan “for setting healthy boundaries with family, friends, and co-workers.” Wikipedia puts its sales at two million copies.
In 2021 the therapist Nedra Glover Tawwab published Set Boundaries, Find Peace, a New York Times bestseller. Its description says, “Healthy boundaries. We all know we should have them in order to achieve work/life balance.”