But the figures the Queensland father rattles off as he retraces his journey to AAP help convey the odds he continues to defy.
Almost 15 years have passed since Mr Twartz, now 53, first contracted sepsis, a life-threatening inflammatory reaction to infection.
Since then, he has survived it about 25 more times and been admitted to hospital 427 times, including for fortnightly treatments.
He has developed an autoimmune disorder said to affect only 600 Australians and the bacterial skin infection, cellulitis, 22 times.
He's "spun the wheel of death" three times, lost four toes and one leg to infection and diabetes and subsequently shed 73 kilograms.
For the dad of two, however, the number that defines his life is $2 million - the amount he estimates taxpayers have spent keeping him alive.
"I don't have that sort of money," he said.
"But in my head, my way of giving back is doing whatever I can bloody well damn do for my community."
A former video store owner and Coles retail worker, Mr Twartz did not plan for a life of community work.
This year, on top of community radio and volunteering as Santa, he became a community ambassador for the Prince Charles Hospital Foundation.
Mr Twartz said yes to the role before a foundation representative had finished asking.
"That hospital, I owe my life to several times over," he said.
He estimates he has spent a full year of his life within its walls, a short drive north of his home in Brighton, a coastal suburb in Brisbane's north.
In his telling, the Chermside facility feels like a country hospital, where staff treat him like family and the name "Big Jon" can expedite a triage.
"When you go to the bigger hospitals, you're a number," he said.
"You're not a number there. You are a person."
Mr Twartz has kept every armband he has been given by the hospital for the past decade, another way he counts his scrapes with ill-health.
"Each one of them is an infection ... is me surviving," he said.
As an ambassador, Mr Twartz sees his job as telling his story and, above all, spreading positivity.
He does it in T-shirts that read "I ran with scissors" or "I'm a retired shark wrestler" - an ironic nod to his amputated leg.
He has even approached the hospital about becoming its official comic relief specialist.
"I thought you had to be a doctor to be a clown doctor," he confessed.
"But you don't, you've just got to be a clown."
Mr Twartz's outlook has rubbed off.
His daughter, who is set to start as a full-time emergency nurse within days, says he is one reason she chose the profession.
His positivity has also left its mark on patients and staff.
Chloe Nguyen, chief communications and philanthropy officer at the foundation, said bringing Mr Twartz on as ambassador was a no-brainer.
"Jon is an incredible human," she said.
"He really lifts the spirits of everybody in the hospital."
After 15 years, Mr Twartz believes the worst may be behind him, but he hopes his story will reach those not yet out of the woods.
"Maybe we've turned a corner now," he said.
"If we have, well, that's even a better story."
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