Placido Domingo — the world's most famous tenor — doesn't consider himself "a tenor by nature," but rather an impassioned performer who's built up his voice over time and swapped roles as his voice evolved.

"Many of my colleagues, the first day they opened their mouths, they all had the tessitura (or texture)," the celebrated Spanish tenor told reporters in Toronto on Thursday afternoon, ahead of his weekend engagement opening the city's inaugural BlackCreek Summer Music Festival.

"It was never easy for me to start singing."

Domingo was born in Spain but raised in Mexico, working every job possible in his parents'  zarzuela (Spanish operetta) troupe.

"I was just building my voice little by little," said the septuagenarian.

For his parents' company, Domingo recalls fulfilling countless roles both on and offstage, from accompanying performers on piano and helping with the chorus to installing sets and distributing flyers in the stands.

Domingo on Toronto 

"I am so busy singing opera, conducting opera, that I have very little time — also between Washington and Los Angeles [operas] — to do concerts," Placido Domingo told CBC News.

"In this case, Toronto, I haven't been here in a long time. I like to be in contact with the public that I remember being wonderful — very, very warm — and [return to] a city that I enjoyed." 

"I have always loved [music]," he said, attributing his unending passion, enthusiasm and work ethic to his parents. "I never had the idea that I would be able to sing opera, much less [have] a career that has lasted this long."

In fact, when he began singing lead roles in 1961, "everybody said 'Oh, Placido, it will last two years,'" the Grammy-winner recalled, laughing.

"Fortunately, they were wrong."

Now 70, Domingo seems indefatigable. Despite being sidelined for a spell after colon cancer surgery in early 2010, the Metropolitan Opera headliner continues to conduct orchestras and sing in operas houses, recital halls and arenas worldwide.

Though he just concluded 15 years as general director of the Washington National Opera, he remains director of the Los Angeles Opera, with which he has been affiliated since its establishment in 1986.

He's always on the lookout for new roles — "There is a lot of repertoire that I still want to do" — despite having played more than 130 over his career.

When asked about how he continues to love singing all these years, Domingo cheekily likened it to "a hobby" and "a sickness."  

"I am very lucky. We are certainly very privileged because what we do is to make people happy," he said, gesturing to soprano Sondra Radvanovsky, with whom he performs on Saturday in Toronto.