Actress Cobie Smulders has opened up about a cancer diagnosis she faced in secret when she was just 25.

Cobie, best known for her role as Robin on How I Met Your Mother, has revealed she underwent numerous surgeries over a two-year period after being diagnosed with the potentially terminal disease.

"I had tumours on both ovaries, and the cancer had spread into my lymph nodes and surrounding tissues," Cobie admits in the new issue of Women's Health, for which she posed topless as a cover star.

The diagnosis came as Cobie's acting career had just begun to take off, a year after HIMYM first premiered.

Thankfully, Cobie beat the disease and even became a mum for the first time at 27, when she welcomed her daughter Shaelyn, followed by a son in January of this year.

The actress and her husband Taran Killam kept the birth of their second child quiet, with Cobie casually revealing the news during a magazine interview a few weeks later. but not divulging her little one's name.

Despite overcoming her cancer, Cobie says she never feels completely safe from it. "I don't think I'll ever feel like I'm cancer-free,' she told Women's Health. 'Now that I'm five years out, I'm trying to think of it as a positive thing and what can I learn from it."

With an established TV acting career and a role in the new Avengers film to boot, Cobie's only advice to young people wanting to emulate her success would be to avoid overworking themselves.

"Just chill the F out, when you're young, you're so worried. I think I was in such a rush to grow up," she said. "I feel like I should've just chilled out, gone back to college for four years and just hung out. Or traveled around the world or something. Just not work so hard."

Sounds like solid advice to us…