Renée Fleming is the sort of person who rarely takes time off. So when fate recently threw a few unscheduled weeks her way, she couldn’t have been more delighted. The superstar soprano had been starring in her first Broadway show Living On Love when it closed prematurely at the beginning of May. This common occurrence on the fiercely competitive Great White Way is often a devastating blow to performers. Yet Fleming took it in her elegant stride and approached the change of plan with her customary optimism.

“The beauty of it is that I now have all this time off, which makes me so happy,” she says, sitting back with a smile in her sunny penthouse apartment on Manhattan’s Upper West Side. “I’ve never had that in my adult life.” Indeed any time off is a rarity for Fleming, who is surely one of the hardest working divas of our time.

In addition to building a phenomenal opera repertoire of more than 50 leading roles, an extensive recording catalogue and a tireless concert schedule, she has also been the go-to performer for countless major international events, including the Beijing Olympics in 2008 and Queen Elizabeth...