Even the most successful people suffer from the dissatisfaction problem. I remember once seeing LeBron James—the world’s greatest basketball player—with a look of abject despair on his face after his Cleveland Cavaliers lost the NBA championship to the Golden State Warriors. All of the world’s wealth and accolades were like straw in that moment of loss.

Abd al-Rahman III, the emir and caliph of Córdoba in 10th-century Spain, summed up a life of worldly success at about age 70: “I have now reigned above 50 years in victory or peace; beloved by my subjects, dreaded by my enemies, and respected by my allies. Riches and honors, power and pleasure, have waited on my call.”

And the payoff? “I have diligently numbered the days of pure and genuine happiness which have fallen to my lot,” he wrote. “They amount to 14.”