Last month, Jacinda Ardern, New Zealand's 42-year-old prime minister, resigned from office, despite the support of a solid parliamentary majority and no challenge to her leadership from within her party. New Zealanders have to go back only six years to find a precedent. In 2016, John Key surprised everyone when, at the age of 55, he made way for his deputy to take over.
A year ago, Ashleigh Barty became the first Australian to win the Australian Open in 44 years. She was 25 years old and the top-ranked women's tennis player in the world for more than 100 weeks. Two months later, she announced her retirement. Likewise, Bjorn Borg, the Swedish tennis champion, retired in 1983 at the age of 26, and Anthony Kim, a rising star of golf, was also 26 when he stopped playing competitively.
Why do they do it? Borg and Barty have given similar reasons. At first, Borg said, he had enjoyed playing and achieving the goals he set for himself. "Basically, over the years, I was practising, playing my matches, eating, and sleeping," he said. "But there's other things besides those four things."
