"It was a bit frightening," admitted Susan Boyle, whose awe-inspiring audition for Britain's Got Talent -- for which Cowell was one of the judges -- aired on television, and exploded onto the Internet, in April 2009.
"I was a bit nervous."
Those nerves didn't come across during her performance of "I Dreamed a Dream" from Les Miserables, which stunned the judges.
"What's the dream?" Cowell asked before Boyle began to sing.
"I'm trying to be a professional singer," she answered simply. "I've never been given a chance before, but here's hoping it will change."
Change it did. Boyle, a Catholic from Scotland, came in second in the competition, and released her first album that November, just six months after she first appeared on television. It was the best-selling debut album of all time, entering the Billboard 200 at No. 1.
Boyle's sixth album, appropriately titled Hope, was just released.
"It's an inspirational album full of inspirational songs," she said. Among them are "Oh Happy Day" and "Impossible Dream," as well as covers of songs by Pink Floyd and U2.
With a concert Oct. 8 in San Diego, Boyle launched her first tour of the United States. She had a number of concerts elsewhere in California. She also planned to perform in Arizona, Texas, Missouri, Kentucky, Georgia, the Carolinas and Florida, where her final concert on the tour was scheduled for Nov. 6.
She said she was excited to visit many new places, and also to travel on a tour bus, something she hasn't done before.
The things she has done, especially in these past five years, are mind-boggling. She sang at the 2010 papal Mass in Glasgow, Scotland, and at Queen Elizabeth's diamond jubilee celebration in 2012. "To sing in front of people like that is very nerve-wracking," she said, though she admitted that she often feels nervous before a performance.
"I love being on stage; on stage is where my home is," she said, but "I'd be telling lies if I said I didn't get nervous."
The youngest of nine children raised in a strong Catholic home, Boyle says she never lost hope that she would be able to realize her dream of a singing career. "I felt that one day, it was going to happen for me," she said.
St. Cecilia, the patron saint of music, is her patroness, though she also has a great fondness for St. Andrew, the patron of Scotland, and Mary. She often accompanied her mother on pilgrimages to Our Lady of Knock in Ireland, and turned to Mary when her own mother died.
"At times of great stress -- when my mother died -- I turn to Mary for support," said Boyle, whose middle name is Magdalane. "I do have a special relationship with Mary, Mother of God, because she's our spiritual mother."
But it was a long road. Though she sang with the choir at Our Lady of Lourdes, the parish she belongs to at home in Blackburn, Scotland, she also went on auditions and even saved up money to record a three-track demo.
She continues to dream -- of a long career doing what she loves, and inspiring other people to persist in pursuing their dreams. "If I can do it, so can they do it," she explained.
"Without God, you can do nothing. The kind of gift He's given me, I have to use for the benefit of others."