The event which is a fundraiser for the Otago Southland Cancer Society will be held on March 14.
She was one of the third of people that were affected in some way by cancer, Ms Shelton said.
Her mother Maree was diagnosed with breast cancer in 2010, when Ms Shelton was 8 years old.
Growing up the illness was a huge part of her life, she said.
"You know, pretty much half my life."
The family received a lot of support during that time, she said.
"I just think it’s really important to try and give back where I can to make sure others get the same support."
Her mother was told she was free of the disease but it returned and she died in 2020.
Ms Shelton, her mother and father lived in London for a time leaving her two older sisters in New Zealand.
There were trial treatments available in the United Kingdom that were not accessible here.
"It got to the point where we weren’t trying to save her, we were just trying to extend her life."
During this time while her father worked and her mother rested, Ms Shelton ran the household while attending school.
"Go to school, come home, do the grocery shopping, make dinner, clean the house, do the washing and then study late at night, and then go to bed, and do it all again the next day."
Her mother became an advocate for making better treatment drugs available to cancer patients in New Zealand.
The best advice Ms Shelton had to offer people facing a journey with cancer was to build a support network.
"Find other people who have been through the same and just talk about it."
People should not try to hold their feelings in.
"It’s a huge roller-coaster, so the best thing to do is just be able to talk to someone else."
She was a member of the relay organising committee and was looking forward to the event.
This was the first time she had taken part in a relay but she had attended other fundraisers.
It was a time to honour those who had died and honour those who were still fighting the disease.
Ms Shelton and her partner moved to Invercargill from Auckland a year ago for a business opportunity.
Invercargill had everything she liked in a city, she said.
"It’s got everything you could need, but it’s still got the quiet life and no traffic and lovely people."
It was the people she liked the best, she said.
