IT will be a painful night for these six University of Tasmania students tomorrow, but at least they will take some pain away for many others.
The sports science students will compete in the Ross Marathon tomorrow in honour of a boy they have never met.
Callum Thomas Bone was just two years old when he died of acute myeloid leukaemia, a cancer that affects the blood cells.
His father, Mitchell Bone, is also a sports science student and got the group together in March.
However, an injury two weeks ago has seen Mr Bone pull out of the event.
Malia Valenciano said Mr Bone inspired them to take on the marathon as a group.
"He has inspired us to believe in ourselves and understand why we're doing it and how important it is to run for a cause," Miss Valenciano said.
Mr Bone is the only one in the group who has completed a marathon previously.
"Until we started no one had done more than eight kilometres," Grace McIntyre said.
"We started really small about six kilometres, that nearly killed us at the start, but we've slowly built it up."
The group ran 36km together a few weeks ago as its final long run before the race.
Tomorrow they will wear white and red Fight Cancer T-shirts to show they are running for Callum Thomas.
"It seemed like if you are going to run a marathon you may as well do it for a good cause," Miss McIntyre said.
The Ross Marathons also includes a half marathon, a 10-kilometre run-walk and a two- kilometre children's event.
More than 715 people have entered, and registrations will be accepted on the day.
Registration fees will be split between the Prostate Cancer Foundation, the Ross Sports Community Group and youth suicide prevention organisation Time Out House.
For more information or to donate visit the Running For Callum Thomas Facebook page.