“This quote is frequently attributed to Epictetus, e.g. by Brigid Delaney, Six ways to make your life easier and more peaceful - by using stoic principles, The Guardian, 22 November 2023. This quotation originates from the 1995 book: The Art of Living: the classic manual on virtue, happiness, and effectiveness, page 23, by Sharon Lebell, a book which "interprets" Epictetus.”

Source: Wikiquote