Roy Young will run his 100th marathon next month.
The 66-year-old will reach his century at Mablethorpe on October 4.
He will run with his 38-year-old son John, of Pontefract, who will be running his first marathon.
They are running in aid of the Candlelighters Trust.
Roy, of Ryhill, is a member of Ackworth Road Runners and also a member of the North East Marathon Club.
John is not a member of a running club . He has done a few low key races over the years but has decided to join his father on his 100th marathon.
John ran his first marathon, The Potteries, in Stoke on Trent in June, 1997.
The only overseas one he has run was in New York in 2002.
Roy said: “We are really looking forward to running this togeather as John has trained hard for this.
“Also we are wanting to raise a few hundred pounds for the candlelighters trust.
“We have quite a few friends joining us on this run some doing the full marathon and others just doing the half .