The 36-year-old was spotted being put through her paces at the GI Jane Boot Camp in Kent, and it looked like she was giving it her all.

Mum-of-four Kerry crawled and ran through obstacles, and was even pictured doing press ups, all with mud smeared across her face.

In some of the shots, the Atomic Kitten singer appeared to be struggling – but she made it to the end of the course, and looked suitably proud of herself.

Kerry and her third husband George Kay's marriage hit a rocky patch earlier this year, but it seems things are firmly back on track for them now.

She tweeted this week: "Just want to thank my lovely husband again for really out doing himself with the cooking #amazing love you @mrgsjkay xxxx [sic]."

Speaking in January, Kerry admitted that working out helps her to manage her Bipolar disorder.

She told Reveal: "The training does help with my bipolar. By staying healthy, I feel a lot happier so continuing to lead this lifestyle helps me to maintain my state off mind as well but I definitely had to work hard to get where I am with it now."