Acute Oncology Specialist Nurse Anthony Thomas and his friend, Emma Peake, are raising money for a local kidney research charity.
They're running a series of events - one per month - including a half marathon which means more than 100km in total.
They started with the Huddersfield 10k known to be one of the worst for its hilliness last week and building up to the Halifax Half-Marathon in June - also fearsome.
Anthony, said: " Originally we said we would only do one 10k and it has developed from there. The hills around Huddersfield are very tough and my legs hurt for days after - not helped by eating too much at a carvery afterwards!"
Ant works closely with patients and colleagues in the renal department of the hospital and Emma lost her step-father to kidney failure when she was young. Her grandma also has kidney failure and has needed regular dialysis for more than three years.
Anthony, said: “As well as Running for Kidney Research, we've now been accepted for the Yorkshire Marathon in October - which I'm quite nervous about. There is a lot of fundraising for all sorts of medical research which is great so we thought it would be good to run for a lesser known research charity - which is local too!
They have paid their own fees to enter the races and now have to pledge £450. They're at £230 so far.
"We've completed our first 10k last weekend and our next one is the Pontefract 10k on Sunday."
The races - following a Huddersfield 10k last weekend, are:
Pontefract 10K - 8th March
Sowerby Bridge 'Flat Caps' 10k (By Eck!) - 5th April
Huddersfield 10k - 25th May
Halifax half marathon (!!!) - 28th June
Halifax 5k - 11th July
York 10k - 2nd August
Slaithwaite Northern Jumble 5k - 26th September
Click here to donate.