Friends Kelea Wendelborn, 7, and 11-year-old Jack Ringer can't hang out together because of the risk of infection.
Both have cystic fibrosis, New Zealand's most common life-threatening genetic disorder, and keep in touch as pen-pals.
Their bodies produce an abnormally thick mucus that clogs the lungs, pancreas and other organs, leaving both children open to severe respiratory and digestive problems.
Kelea's mum Anthea Wendelborn says she looks and acts like an average child.
But the "invisible disease" plays havoc on the inside.
"There's not one day in our lives where we don't think about and plan for cystic fibrosis."
Mrs Wendelborn and Jack's mum Jo Ringer, from Coatesville, met through the Auckland branch of the Cystic Fibrosis Association, which will receive $15,000 from proceeds raised through this year's Ports of Auckland Round the Bays on March 10.
Mrs Ringer says the charity has had a huge impact on her life.
"We're all going through different journeys that are the same, if that makes sense."
Mrs Wendelborn, who is co-chair of the organisation, is thrilled to see her organisation as one of several children's charities set to benefit from the annual fun run.
The money will help buy nebulisers needed for physiotherapy for the 125 families in Auckland affected by cystic fibrosis.
Jack and Kelea do 550 hours of physiotherapy and take about 9000 pills each year to keep them healthy.
They also need to do frequent exercise and follow a high-fat diet which Mrs Wendelborn says is the "food pyramid upside down".
Hygiene is also crucial and Jack and Kelea always carry hand sanitiser with them.
Mrs Ringer and Mrs Wendelborn say they spend hours and hours cleaning.
Something as simple as a common cold could lead to a two-week stay in hospital for their children.
The two mums will be racing in Ports of Auckland Round the Bays as part of a team supporting Kelea and Jack.
They hope to raise $2000.
Mrs Wendelborn says she thinks about Kelea each time she struggles for breath during training.
"We expect our kids to do exercise to keep well so this is a great opportunity to be role models and get out there and hit the pavement."
Mrs Ringer is also determined to finish the race.
"Even if I get dragged around I'm going to do it," she says.
Ports of Auckland Round the Bays is an 8.4km race around the waterfront.
It is co-owned by The Auckland Joggers Club and Fairfax Media, owner of Suburban Newspapers and the Rodney Times.
Go online to roundthebays.co.nz to register and for more information on the event.
- © Fairfax NZ News