Playing 80 minutes of NRL requires endurance but it pales in comparison to what Sean Clarence will achieve with his inspirational #Neverrest campaign.
To raise awareness and funds for cystic fibrosis research - the respiratory disease that claimed his brother Nathan Clarence - Sean is set to run a marathon and complete 10,000 push-ups and 1500 pull-ups over 24 hours.
His journey begins at ANZ Stadium before Thursday's blockbuster clash between the Rabbitohs and Roosters and ends at Bankwest Stadium the following night for the Eels-Sea Eagles match.
Parramatta - whom Nathan fervently supported – and South Sydney have proudly gotten behind the initiative.
"We wanted to do this challenge while Nathan was still with us but unfortunately we lost him in January," Sean told NRL.com.
"That's the reason we're doing it – [cystic fibrosis] kills people. We got an actual taste of it. We're now trying to raise money and help find a cure.
"My brother was one of those really lovable guys. Because of what he had, he didn't really care about what car he drove or what he did for work or anything like that.
"He was really focused on the time he spent with his family and friends. He was just a really genuine, awesome and amazing guy that I miss a lot."
One in every 2500 Australian babies is born with cystic fibrosis. Sufferers develop an excessively thick and sticky mucus in the lungs, airways and digestive system that makes every breath a struggle.
As the #Neverrest campaign explains, those with cystic fibrosis start life at the base of Mt Everest.
Lung failure is the main cause of death for cystic fibrosis patients, with an average life expectancy of 38 years.
Sean, a gym owner, doesn't have any experience with endurance sports but wanted to prove that you can accomplish anything if you're prepared to fight - much like his brother did just to breathe.
He will kick-off the challenge at ANZ Stadium on Thursday at 7pm by knocking out his first round of push-ups and pull-ups before heading onto the field at half-time of the footy to speak about the campaign.
Next, he'll run to Bankwest Stadium – about 12km – to prepare for the remaining six rounds of the remarkable effort.
"Each round will be approximately 1500 push-ups and 250 pull-ups," Sean said.
"I do that by doing 13 or 14 push-ups and two pull-ups every minute for two hours, nonstop. And then I run five k's [kilometres] which should take around 30 minutes. I'll get about a 50-minute rest and do that on repeat six times.
"Hopefully, if I don't crumble too much, I'll get it done."
Having already raised $17,000 for Cystic Fibrosis Australia, Sean is hoping to total $65,000 for a particular reason.
"The story goes that there was once a girl in hospital with cystic fibrosis who was asked what she had. She couldn't say cystic fibrosis, so she said 65 roses," Sean said.
"That's why CF [cystic fibrosis] uses the rose as their logo … We thought 65 was the number we'd aim for. What we raise is going to be a drop in the ocean for what's needed to find a cure for cystic fibrosis – but it's our drop."
The Rabbitohs will also wear special red socks with a white rose stitched into them for the cause.
Souths have a connection to the disease through Pat Borg, the group fleet sales manager of the club's official car partner Suttons, whose daughter Isabella has cystic fibrosis.
Borg takes part in the annual 65k 4 65 Roses Walkathon fundraiser and organised for the Rabbitohs to support Sean's endeavour.
In addition to the #Neverrest campaign, Sean will push the "Red Peg Challenge" on social media to see how many push-ups athletes can manage with a peg on their nose.
"The idea is it mimics the limited lung capacity of people with cystic fibrosis," Sean said.
"It's definitely not the same but putting the peg across your nose obviously makes it a bit harder to breathe."
Given he completed roughly 150,000 push-ups and more than 20,000 pull-ups during nine months of training, Sean is keen to mix up his workouts once the campaign is finished.
"It's actually going to be nice to do something different afterward, to be honest!"