Family and friends dressed in Christmas costumes will push a wheelchair 22 miles from Crawley to a hospital in Sutton.
Trica Hayward, 43, of Tolgate Hill, set the challenge after her 17-year-old son David got the all clear at The Royal Marsden Hospital Sutton last November.
David underwent chemotherapy treatment at the hospital for more than three years.
Trica said: “David had to do the trip every week and we thought it would be nice for him to remember the last few trips as a positive rather than a negative thing.
“Every time he went it was because he was so ill.”
Trica’s husband Steve, 45, and daughter Sarah, 18, will join David and their supporters in taking turns to push a wheelchair with one of them in it on April 12.
She said 13 volunteers had agreed to take part in the challenge so far.
Everyone but David will be dressed as Santa Claus - he will go as Rudolph.
The family bought the costumes during the festive period.
Trica said: “It’s going to be very hard because you’ll have hills, main roads and pathways.
“As a family we’ve changed. My priorities in life have changed, it’s not about taking it’s about giving.”
The family is raising money for charities CLIC Sargent and Young Epilepsy.
CLIC Sargent helps children living with cancer.
Trica works for Young Epilepsy and wants to help it buy a new minibus. For more, visit uk.virginmoneygiving.com/fundraiser-web/fundraiser/showFundraiserProfilePage.ction?userUrl=TricaHayward