Martina McBride On Life in the Country Spotlight

More than 15 years ago Martina McBride was working on and off with her husband on the Garth Brooks tour helping to sell T-shirts when Brooks made her a deal: If she got a record contract, he'd give her a shot at being a star.

She landed a contract in 1991 and afterward performed an impromptu a cappella song for Brooks.

"It was right after that he'd said, 'Well, if you don't mind, I'd like you to open my tour next year, all my dates,'" McBride said, recalling the story for "Good Morning America's" Robin Roberts. "So I guess I passed the audition."

VIDEO: Martina McBrides Home MoviePlay

From there it was a life of packed stadiums, chart-climbing hits and a durable stardom uncommon in an age of easy-come-easy-go starlets. Even having three children hasn't stopped McBride from rocking through her 40s, as they often traveled with their mom to gigs around the world.

But she's hardly the average mom. McBride recently appeared bikini-clad on the cover of Shape magazine alongside LeAnn Rimes and Julianne Hough, country singers half her age.

"I had sort of questions about doing something like this because I always stress to my girl's [that] it's about being healthy, you know?" McBride said. "That's what I wanted to show with this cover, is that at any age, the important thing is not to be an important size, [it's] to be healthy."

VIDEO: Martina McBride talks about how music can change lives.Play

Singing From Seven

Even before she was an international superstar, McBride was no stranger to the stage. She started singing in front of audiences before most kids learned their multiplication tables.

"There was a little club in our hometown, and my brother and I would go and play for about an hour," she said. "And then, you know, at 7 years old, we 'd have to go home and go to bed. So we eased into it, actually. But just being on stage and being able to be a part of that was so exciting.

"I loved to perform and to sing."

McBride and her husband, John, moved from Kansas to Nashville in 1990. That's when John got the job with Brooks and McBride got her start as a country powerhouse.

Nearly 20 years and 23 top 10 hits later, McBride has no plans on stopping anytime soon even in the face of much younger competition.

"In this business, you always have a little bit of fear of 'When is it going to be over?' You know what I mean?" she said. "You just have to hang on and do the best work you can. And love your fans, and love what you do."

And as she prepares to rock out as part of the "In the Spotlight With Robin Roberts" Nov. 10, she said she loves her busy life.

"I feel like I was put here to sing, in a way. To touch people's lives, I mean, that's what music does," she said. "My dad, every once in a while, he'll ask me, 'Well, are you still having fun doing this?' And I'll say, 'Yeah dad I am. I'm still having fun.' "