On Sunday the KidzWish ambassador and event founder will join hundreds of others for the seventh annual walk from the Sea Cliff bridge to Windang bridge.

All funds will go towards the services and programs offered by the Illawarra children's charity, which are invaluable to kids like Kiara.

"Kiara has Down syndrome and hydrocephalus (fluid on the brain), and has had to undergo 31 operations,," her mother Vanessa said.

"She's had open-heart, lung, and stomach and bowel surgery as well as surgery to remove a brain tumour, and KidzWish has been there supporting us every step of the way.

"We'd encourage people to support KidzWish fundraisers, as they really make the journey easier for kids and families in need."

Lake Illawarra resident Mr Hamilton started the challenge to inspire people to help others.

"I've got three or four families I've known for 20 years that have kids with special needs and I see how hard it is for them," he said.

"One of my friend's kids has had a brain tumour since he was born. He's had it removed a few times and now he's going through radiation treatment."

Mr Hamilton also had his own health issues a few years ago after suffering a stroke, and hopes the event will also encourage people to get active.

"I want to show people that age or having a stroke isn't a barrier, because if I can do it so can others," he said.

Participants can opt to walk all 40km, or part of the course said KidzWish spokesman Karouna Michael.

"People can take their pick and customise their own course as we have seven different sections to cater for people of all abilities," he said.

"Taking part in this challenge looks different for everyone. Some will train their hardest to complete the entire challenge, many will customise their course and more will attend the family fun day at Club Windang with their friends — all choices are welcome."

Register at www.kidzwishfoundation.org.au/our-events/kidzwish-bridge2bridge-walk/