"I just want to encourage people to live their best lives while they can, because none of us know what is around the corner," she said.
Martelli runs online fitness and personal training business, Strong Woman. It started as a Facebook page sharing her post-cancer recovery and then grew from there.
As Martelli regained strength, she realised her passion for helping other women - particularly those who were recovering from illnesses.
She went on to become a qualified personal trainer.
"I'm super aware of my health. And that is why I started Strong Woman - we all only have one body. And we need to look after it," she said.
"After that journey, I started up a Facebook page. I got myself from being in bed, back to running again.
"At first I was just walking to the end of my letterbox. Then once I had done that it was walking 1 kilometre. Slow and steady wins the race.
"I definitely look at life a little bit differently now. You definitely appreciate the small things more. I find myself more grateful for things that weren't as important to me before."
An important part of Strong Woman was to support and inspire woman to move their bodies in whatever way possible.
"I have dealt with quite a few ladies over the years that have had cancer or just an illness that they live with. It means the world to me," she said.
"It's about supporting and inspiring other women to look at the journey I have had – and think, if she can do it, I can do it.
"The whole philosophy is about building a routine of moving your body in whatever way serves you."
Only last year she was diagnosed with a "pretty gnarly" form of arthritis, which presented a new set of challenges.
It left her unable to run and forced her to change her exercise routine. Arthritis originated in her feet but had since spread to her shoulders and hips.
"Some days I am in pain, and I struggle to get out of bed. Other days I feel good. I have had to rethink my exercise routine," she said.
"But I can only do the best that I can do. You have to take the good days and the bad. When things are good, you just have to live life. And when they are not – you just have to ride it out."
Martelli said she celebrated being five years cancer-free with a weekend in Taupō.
"I was getting regular blood tests the past five years. They have finished now - so I am excited about that. The oncologist said to me 'that's it'. I was signed off."
