Headteacher David Naisbitt will run the Sheffield Half Marathon spurred on by the memory of his late nephew who died aged two.
David, from Nether Edge, is hoping to raise funds and awareness of Bluebell Wood Children's Hospice where Sam Sparkes was cared for before his death.
Sam was diagnosed with mucolipidosis II, I Cell disease, when he was six months old and he died in December 2009. He was among the first children to stay at Bluebell Wood, in North Anston, which opened in 2008.
David, 44, who lives with his wife Jessica and sons, Josh, 14, and Ben, 11, said: "The vital thing about Bluebell Wood is that it offers support to the whole family. Sam needed 24-hour care and a variety of medication, so going to Bluebell Wood meant that the pressure was taken off his parents while they could rest assured that he was getting the care he needed."
Sam and his family, including Sam's mum Rona, dad Jon and older sister Freya, then aged four, were able to receive additional medical support and respite care.
David, headteacher at Oakwood Technology College in Rotherham, said: "It is easy to take what Bluebell Wood offers for granted. I hope that people never have to experience what Rona, Jon and the rest of the family have been through, but if they do, there should be provisions like Bluebell Wood available to them."
It costs £3 million every year to run Bluebell Wood which recives no statutory funding.
Sarah Champion, chief executive of the hospice, said: "The support of people like David is vital for us to continue helping as many families as we do."
The SIG Insulations Sheffield Half Marathon and 3k Fun Run takes place on May 27 at Don Valley Stadium from 9am.
To sponsor David visit www.justgiving.com/David-Naisbitt.
