There was a time when Deborah Voigt didn’t think she would be an opera singer. It came on slowly and randomly, she said in a phone interview from her home in New York.

“At 15, when I started looking for a voice teacher, I happened to find an opera coach. I just knew I loved to sing and I elicited a response in an audience. I grew up singing gospel and Carpenters’ songs. If my teacher had been into musical theater or gospel, that’s where I would be today.”

Either way, you knew she was destined to be a star.

Despite winning awards, it wasn’t until her official debut with the Boston Lyric Opera in 1991 that Voigt got the opera message.

New York Times writer John Rockwell just happened to be in the audience of Strauss’ “Ariadne auf Naxos” for another story and ended up launching her career.

Her Ariadne “revealed one of the most important American singers to come along in years,” he wrote.

And she still is. Now, coming off her debut as Brunnhilde in Robert Lapage’s reinvented Ring Cycle at New York’s Metropolitan Opera last season, Voigt will serenade the mountains of Idaho as this year’s guest artist at the Sun Valley Summer Symphony.

The symphony brings some of the best players in the country to Idaho for a 10-day, world-class summer music festival led by conductor Alasdair Neale and featuring some of the best and most important classical artists.

If you missed Voigt at the Met, you can hear her perform music from “Götterdämmerung” and “Die Walkure” on opening night, which is July 30. She also will perform music by Strauss and others as part of the In Focus series on July 27.

This is Voigt’s second time performing in Sun Valley, a spot she has grown to love. She performed in 2009.

“It’s just such a beautiful place to be,” she says. “I went horseback riding and hiking. But sitting on that stage and looking out over the mountains is breathtaking. It really is God’s country.”

Singing Wagner takes a particular kind of voice, and Voigt definitely has it.

“It has to be large, obviously, and somewhat steely so that it will carry through an orchestra. It must have stamina to last an evening and it requires a lot of concentration,” she says. “There’s a lot being said with the music without singing, and, today with HD cameras on us, you can’t let your body (relax) for a second because you never known when you’re on camera.”

For Voigt, the rigors of the Met’s Ring Cycle (four epic operas performed in succession about the battle between the gods of Valhalla and humanity over the magical ring that controls it all) took a toll.

In the final weeks of “Götterdämmerung,” the last of the four operas, she discovered that she needed a hip replacement, which she will still be recovering from while in Idaho.

That’s just one of the challenges she has faced in her life. She will deal with that and others in her memoir that’s due out in 2013.

The book will reveal Voigt’s life both on and off the stage — and not just her triumphs. She will revisit her most personal struggles, she says.

“It is difficult writing, and it feels like it’s never going to get done,” she says. “But I want to make this different. There are enough books about opera singers’ stage lives, and the opera folks will be interested anyway. I’m hoping for a broader audience.”

The book will reveal more than just the obvious. It will look at how the events in her life influenced her on-stage presence and vice versa, she says.

“I’ve had horrible luck with romance and choosing the wrong people to have in my life,” she says. “It’s no secret that I used to be a very large lady, and that struggle is certainly a part of my life’s story.”

Voigt was famously fired in 2004 from a production of Strauss’ “Ariadne” at London’s Covent Garden because the director felt she was too large for his vision of the character, who was scheduled to wear a “little black dress.”

The incident was painful and afterward, she underwent gastric-bypass surgery that fortunately did not affect her voice. She lost more than 100 pounds and made a triumphant return to Covent Garden in 2009.

At the height of her weight issues, she sang the role of Sieglinde in “Die Walkure,” a character on a very different journey than Brunnhilde.

“There were so many things I could relate to in that character: the feeling that she’s trapped, and at the time I felt trapped by my weight, trapped and hopeless. But there’s something that keeps her going, and I found that, too. And of course I was singing opposite Placido Domingo. I don’t know if it’s faith or sheer determination to just do your best no matter what, but you get through.”