They're one of the music industry's most long-lasting and inconspicuous couples, and rarely make official public appearances.

But now Gwen Stefani has opened up about the secret to her lasting relationship with husband of 12 years Gavin Rossdale. 

 "You get what you put in," the No Doubt front-woman and award-winning solo pop artist tells The Huffington Post. "I've learned that from my parents, who have been married for almost 49 years - proof that the more you work at marriage, the more amazing the rewards."

Speaking on on America's Today show earlier this year, the 45-year-old said "'If I look back on the whole thing (her marriage to Rossdale) the one thing that's been constant is that we both want the same thing."

"We both want to be married. We both want to be good parents and so I feel really proud of what we've done together and that we don't...You're gonna get me crying, no don't, I'm going to get all emotional! But I am really proud of it."

The couple have three young sons - Kingston, 8, Zuma, 6, and Apollo, 1 - and Gavin Rossdale is also father to English model Daisy Lowe, 26, with Pearl Lowe.

Family life is key to Stefani, speaking about a childhood tradition she's continued for her boys.

"When I was growing up, Santa Claus would cover the living room doorway in wrapping paper so we kids couldn't peek at what was under the tree. Our parents would count to three, and then we'd crash through the paper to get our presents. It's the craziest thing because now Santa does the same thing for my kids. Weird, huh?"

The star shot to fame as the co-founder - and only female member - of pop-rock band No Doubt and quickly became an icon for 90s fashion, championing crop tops, bindis and double topknots. She says her style inspiration was her "eighth-grade self".

"In 1982, I was into ska music, James Dean, and the Latino culture in my Southern California neighborhood. As a result, I tried to dress outside the box, different from what the other kids were wearing, with a laid-back vibe - and big accessories. More than 30 years later, that's still my look!"

Stefani established her own solo career in 2004 before reuniting with the band to release their seventh album in 2012, however she still regards her first performances as the best in her career.

"Early in our career we performed in a pub in Munich where everyone knew all the words to "Don't Speak." It was incredible. And what's really insane is that I recently worked with a photographer who was at that same show as a 13-year-old, and he had tried to take off my shoe!"