There's no better training for the gruelling Coast to Coast than the exposed high country behind Elise Cassidy's Culverden home.

The 36-year-old spends most days, when she's well, in the North Canterbury hills or her neighbour's man-made lake.

"I want to show my kids exercise and moving and going through hard times creates a stronger person.

"Building resilience is important," she said.

And it's training for the 243 kilometre adventure race – taking athletes from the South Island's west coast to the east – that got Cassidy through a challenging 12 months.

"A year ago, I'd just started my first round of chemotherapy because I was diagnosed with stage three bowel cancer."

She'd been fighting to have her symptoms investigated for months. It was only after she'd fallen pregnant that a scan revealed a five centimetre tumour.

"They thought I had irritable bowel disease and put me on the list for a colonoscopy ... but once I called the doctor and told them I was pregnant, they dropped me like a hot stone.

"So then I went to a specialist and said 'What can you do?'

"They did an MRI and found this lesion, and the baby in there... and then finally did a colonoscopy and saw the tumour, and the lymph nodes lit up," she said.

Cassidy's since undergone pregnancy-safe chemotherapy, had surgery to remove the tumour and given birth to her third child – all while training for the Coast to Coast in 50 days' time.

"I just didn't want to be in a hospital bed or feeling sick. I just wanted to move my body and appreciate what I've got," she said.

Cassidy's teamed up with multisport legend Nathan Fa'avae, who's designed a custom training programme for her.

"He's been really helpful and it suits me to a tee ... he knows I've got three kids and I'm limited on time so he's nailed it and so far I've gone and achieved most of the sessions."

While she finished chemotherapy five months ago, she still has "hangover effects" from the treatment.

"I've got neuropathy – so my feet, I still can't feel them well," she explained.

"I get tired and fatigued easily," she continued, joking that "adding a third child to the mix probably didn't help".

As it stands, Cassidy is cancer-free – now on quarterly bloods, six-monthly colonoscopies and annual CT scans.

"I'm pretty stoked with how I took it on – I've always tried to be positive throughout the whole thing and not let it get me down.

"And I've been vocal around what you need to look out for when you do have bowel cancer – and if you are pregnant, or something feels wrong in your gut – go get checked and advocate for yourself, because I was told 'You're young, fit and healthy – it won't be cancer'," she said.

Cassidy will proudly don a special race kit in 50 days' time to honour her plight, and those impacted by the disease.