The No Doubt star stunned fans in August (15) when she and Gavin announced plans to divorce after nearly 13 years of marriage.

Gwen has been throwing herself into her work ever since and instead of clearing her mind with a good fitness session, she has been working on her soul.

"I haven't really been working on my physical appearance," she tells, when asked how she stays in shape. "I've been working on my spiritual exercising. And really trying to connect and be grateful, considerate, being present and living in the moment, and so that's where I've put a lot of my exercise right now.

"So, if that's what you're seeing, that's awesome, because I've been working really hard on that."

Gwen has yet to speak out directly about her impending divorce, but she recently admitted the video for her new single Used to Love You, in which she sobs as she sings, was a "very real" reflection of her emotions.

The track features lyrics like, "I thought I was the best thing that ever happened to you/I guess nobody taught you how to love", and she insists it's pretty clear she was writing from personal experience.

"It's funny when people try to go so deeper (sic) into a song that's already so spilling my guts, it's like, what else can I say...?" she says.

Gwen's comments emerge days after she was caught off guard during an appearance on U.S. breakfast show Today on Tuesday (27Oct15), when she was quizzed about the inspiration behind the tune.

"Oh my God, put me on the spot!" she exclaimed. "What I'll say about that is that I've never put a record out where I'm actually going through things in real time..."

"I wrote that song a couple weeks ago, and then I sat in front of a camera in a dressing room, randomly not making a video, just to do some video for the screens behind me (onstage), and then it went out and it was the (official) video. It's all very real."

Gwen and Gavin, who are parents to sons Kingston, Zuma, and Apollo, are reportedly close to finalising their divorce after signing off on an agreement to split their assets and share custody of their boys.