The comedian and actor is used to performing in feature films and television, including The Castle and The Secret Life of Us, but this production marks his musical theatre debut.
"I'm feeling every one of my 50 years, I'll be honest, but I love it hard," he said.
After a successful Melbourne season, the Tony Award-winning musical has galloped into Sydney.
Based on the 1975 film Monty Python and the Holy Grail, Spamalot is a musical parody of Arthurian legend, with Curry taking centre stage as King Arthur.
While he had grand plans to complete six months of cardio before starting the production, those never materialised.
"I loved it so much, but if it were a longer run, it might actually kill me," he said.
"Physically, it's a lot ... and I don't go to the gym or anything."
Set in medieval England, the show features a newly crowned King Arthur recruiting a band of knights for a perilous quest to find the Holy Grail.
Along the way, they encounter eccentric characters, absurd challenges, irreverent humour and unexpected moments of self-discovery.
A self-confessed "show-off", Curry said the production means "everything" to him.
"It was my first musical theatre production, and for it to be this one is perfect because it's so fun, so energetic and so ridiculous," he said.
"But so am I, so it's right up my alley."
Although Curry grew up loving musical theatre, often attending shows with his mother, he is unsure whether he has been bitten by the theatre bug.
For now, he is relishing the chance to connect with audiences in a way that screen acting rarely allows.
"There's nothing like a room full of people laughing at the same thing," he said.
"Conversely, there's nothing like a room full of people not laughing at something you've chosen to do."
Curry said audiences had been "amazing", embracing the production's irreverent humour and its cast.
For him, the show's appeal lies in its ability to offer audiences a break from the outside world.
"This is two hours of pure escapism - for us and the audience," he said.
The production is playing at The Star Sydney from October 15 to 18, before moving to Western Sydney's Coliseum Theatre from October 22 to 25.
Joining Curry for the Sydney season is Marney McQueen as the Lady of the Lake and Jamie Rolton as Patsy, alongside Nick White, Gareth Isaac, Jesse Vasiliadas, Noah Skape and Ethan Jones.
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