Her mother Jacine Geaves said her world immediately changed when she found out her daughter had cancer.
"When Josie got sick, it was hard, not just emotionally you don't even know what leukaemia is so that first was the biggest challenge, trying to find out what it even meant because us, we just thought cancer equals death," she said.
She said the Child Cancer Foundation meant "everything" to her family as they supported them throughout
"[The] Child Cancer Foundation has done everything - shopping, paid for our power, paid for her dad to come and see us, just paid everything.
"They even paid for us to buy heaters when we got out of hospital because it was cold and our house wasn't insulated, anything that you need and you can't afford they can help you with."
Josie hopes her words will help other children come to terms with their illness.
"If I was talking to other people who are sick I would say it's all going to be okay," she said.
"When I was sick it made me feel sad because I didn't get to be with my dad, and I missed going to school."
Geaves said she became emotional while reading what Josie had written in her diary.
"We just couldn't stop crying, tears on tears all the time. But they helped us, writing stuff down helps.
"The diary entries . . . were really cool, they were basically memories for her. Some of them were sad because she had to put herself back in that predicament . . . we've come a long way."
Child Cancer Foundation chief executive Robyn Kiddle said the campaign highlights that "no two families' cancer journeys are the same".
"Every donation made during the March appeal will go towards ensuring these children and their families always feel supported when walking the cancer journey."
As the Child Cancer Foundation receives no direct funding from the Government, it relies on donations.
Kiddle said those donations are used to help children like Josie and their families.
"It might be assistance with groceries, accommodation, travel costs, or one-on-one time with a family support co-ordinator, our team is here to maintain hope and provide strength. For families, parents and of course, the child."
Those willing to donate can go to childcancer.org.nz to contribute or donate to street collectors on March 17 and 18.