Not because the front-rower is a sucker for punishment, but because he is determined to raise funds and awareness for Parkinson's disease
Inspired by his father-in-law Gav's toughness and fight against the illness, Henry will run 10 laps of the 6.5-kilometre path that goes over the Nepean River.
Diagnosed 13 years ago at age 38, Gav's ability to fight through adversity inspires the Panthers prop daily.
"He's an absolute trooper," Henry said.
"It progressively gets worse and it got to a point (about six years ago) where he couldn't work anymore.
"But you never hear him complain whatsoever. He doesn't stop, doesn't let it hold him back. He's an absolute legend."
Henry hopes to raise $5000 from the October 10 run, but the main goal is increased awareness.
He has known Gav from his days working with Henry's older brother for a steel erection company in central west NSW and growing up in Blayney.
"I just want people to have an understanding of what Parkinson's is, and how it affects someone," Henry said.
"For him it looks like anywhere from being real dyskinesia, so moving around heaps, can't sit still, restless legs.
"And then when (the medication wears) off he'll freeze, so he can't walk. And all in between, constant back pain, and all that stuff.
"Gav gets a lot of looks and stuff whenever he's out in public, so it's more to raise awareness so people understand."
It is not the first time Henry has tested his body outside of football.
He previously completed a 50km hike through the Blue Mountains, which the prop reasons would have been a lot harder given the stairs and elevation.
The idea for this one came while seeing clips of the backyard ultra, with Henry deciding he wanted to do something similar for charity while honouring his father-in-law.
The 25-year-old plans to take breaks between the 6.5km laps, and has an open invite for people to join him for the runs and chats in between.
The challenge this time may be that defeating Newcastle on Sunday would mean a grand final just six days before the run, with the hope of premiership celebrations in between.
"It wouldn't be the best of prep leading into it," the Perth-bound forward quipped.
"As the day goes on, I'd say the spells will get longer.
"It's more just getting out there, doing it for a good cause. I'm not too worried about the distance at all.
"It'll obviously be tough. But it'll be a great day. I feel like people will jump in, have a yarn, and all it is is just raising awareness."
