He will clock up 53 miles before the end of the year.
And with each step he makes, Joe Green will have his late son Seth at the front of his mind.
Mr Green and his wife Beki lost baby Seth, who was stillborn, in December 2015.
Stillbirth and neonatal death charity Sands supported them through the tragedy.
And now Mr Green, of Smawthorne Lane, Castleford has planned a quadruple fundraising challenge to give something back and support the charity’s work.
He said: “Losing Seth was absolutely awful. I can’t even put it into words. It didn’t feel like it was really happening.
“It was obviously a really hard time for both of us.
“Me and Beki had each other and had our families but some people don’t even have that.
“Sands were there for us to talk to, as they are for any parent going through what we did.
“Just knowing that there was somebody there for us and that we weren’t alone made all the difference.”
Mr Green, a plasterer by trade, is currently in training ahead of the first of his four challenges. He has signed up to do the Lincoln 10k on April 2.
And he will then step his running up a notch by tackling the Leeds Half Marathon on May 14, before being joined by friends Sam Payne, Richard Scott and Tommy Skerrett - Team Mud, Sweat and Beers - for the Yorkshire Tough Mudder event on July 30.
His fundraising will finish with his biggest event, the Yorkshire Marathon, on October 8.
Mr Green, 32, said: “It has taken me a year or so to decide what to do to help Sands because we will be forever grateful.
“I wanted to do something big and a bit different as a way of saying thank you.
“Training is going okay and I’m finding doing the Pontefract Park Run every week is brilliant. I feel like I push myself more to go faster because there’s other people around me.
“The 10k, which is the first one, that’s something I know I will be able to do but the other ones, I’m feeling a bit more nervous about. It’s a long way!”
The couple, who went on to have daughter Betsy in December, praised Pinderfields, Pontefract and Leeds hospitals for their support during and after both pregnancies.
And they said they also received help from other charities including 4Louis, which provides memory boxes for parents who have experienced stillbirth or who have lost a baby or child.
Mr Green, who has already raised more than £800 in sponsorship, said: “I hope in the future to continue fundraising and support some of the other people and charities who helped us as well.”
To make a donation, visit www.justgiving.com/fundraising/Joe-Beki-Green
Support from SANDS charity
Sands is a national stillbirth and neonatal death charity.
It offers support to anyone affected by the death of a baby including providing a helpline.
It also works to improve the care bereaved parents receive from professionals, promotes research to understand how and why babies die and help reduce the loss rate, and raises awareness of baby death across the UK.
The charity was founded in 1978 by bereaved parents who felt there was no access to support following the deaths of their babies.
For more information, visit www.sands.org.uk