The mere thought of pounding through 26.2 miles to complete a marathon is a daunting task for anyone.
But Sheffield Children’s Hospital has come up with a marathon that everyone can do, no matter how unfit you think you might be.
Team Theo’s Virtual Marathon gives every entrant the entire month of August to complete their marathon. They can clock up the miles a little bit each day and record it on their online profiles.
The campaign aims to raise £30, 000 towards the cost of a liquid chromatography tandem mass spectrometer - a £200, 000 machine that can diagnose vitamin D deficiencies.
And while the virtual marathon is designed for everyone - there are undoubtedly some extraordinary people putting in a marathon effort for the cause.
Reporter Lee Peace highlights a few of them.
Life has been a daily battle for Sheffield lad Billy Roe since he was born.
The eight-year-old Arbourthorne Primary School pupil suffers from Prader Willi Syndrome, a rare genetic condition which means he cannot switch his hunger off.
His family have to keep him on a strict diet and exercise plan to keep his weight under control and stop his muscles from wasting.
But his proud mum and dad say the one thing his chromosome deficiency will never affect is his determination.
It is what's is driving him on to walk a marathon for the hospital, which has cared for him since his mum rushed him to the accident and emergency department as a tiny and limp one-week-old.
Billy tires easily so his mum Leanne, four-year-old sister Phoebe and dad Mark, a 32-year-old fabricator, are walking at Billy’s pace. He also plans to clock up a few of the miles on his tailor-made TomCat trike, designed for children with disabilities.
Mum Leanne, aged 32, of Wybourn, said: "Billy amazes us every day with his strength of character and his easy-going personality."
To sponsor Billy visit https://teamtheovirtual.everydayhero.com/uk/billy
Young footballer Cameron Connor is walking his way back to match fitness after undergoing emergency surgery at the hospital.
The Forge Valley School pupil was on a May Bank Holiday trip to Glasgow to cheer on his beloved Rangers against Celtic when he suddenly collapsed.
Hospital doctors in Scotland couldn’t work out what was wrong and worried dad Douglas drove him home to Hillsborough - where Cameron collapsed again within minutes.
The 12-year-old later underwent a major operation to stop an internal bleed.
Dad Douglas, a 45-year-old print buyer, said: "It was every parent’s nightmare. He was rushed by ambulance to Sheffield Children’s Hospital and everyone went into overdrive.
“We must have met 20 doctors from three different medical teams who were all trying to find out what was wrong.”
They discovered Cameron was suffering from Meckel’s diverticulum, a congenital disorder in the intestine.
But three months later, Cameron, who plays for Hillsborough Pumas Junior Football Club, is determined to walk a marathon in a month by declining lifts from his parents and avoiding bus rides.
A chunk of his challenge will also be completed while he’s on a family holiday in Italy and he already has around £300 in sponsorship pledges.
Douglas described the hospital staff as "fantastic" and added that his son is "determined to get match fit again."
To sponsor Cameron visit https://teamtheovirtual.everydayhero.com/uk/cameron
Children’s hospital patient Mia Constable will always be able to remember every mile she has clocked up for the appeal.
For the nine-year-old is uploading regular blogs to YouTube from her early morning nature walks.
Mia, who lives in Goole, has almost completed the marathon challenge with her mum Sarah - and has loved every minute.
She said: "I like the peace and quiet. We sometimes see a rabbit or two and lots of wild flowers."
The youngster added she was happy to help the hospital after staff treated her when she was a baby.
She fell seriously ill with suspected meningitis at less than two-months-old and was later diagnosed a severe dairy intolerance which had caused reflux and burned her oesophagus.
Mum Sarah, aged 35, said: "The fact that Mia is fit enough to do the Virtual Marathon is thanks to doctors at the hospital."
Her online fundraising page is at https://teamtheovirtual.everydayhero.com/uk/sarah-jane
Four members of the hospital's world-renowned chemical laboratory are also striding forward in the marathon challenge.
Phil Craddock Jones, laboratory manager, and biomedical scientist Helen Chapman are taking part by running and walking during the month.
Meanwhile clinical scientist Sharon Colyer, aged 30, and Leanna James-Ellis, aged 33, a biomedical scientist from Maltby, are multi-tasking.
They are doing the virtual marathon as part of training for another gruelling fundraiser for the same appeal later in the year.
Sharon and Leanna are two of a six-strong team from the labs who will be competing in the corporate relay at York’s Yorkshire Marathon on October 8.
Sharon, of Kelham Island, said: "We are killing two birds with one stone - our runs and walks for the Virtual Marathon are getting us fit for our October run."
Keen runner Leanna wanted to take part because the fundraising appeal will directly benefit the place where she has worked since she was aged 18.
Other members of the relay team - named the Speedy Scientists - are Kate Fagan, Nicola Platt, Louisa Smith and biomedical scientist student Sonal Ilyas.