I hurt everywhere. My legs hurt. My chest hurts. I haven't pulled on a T-shirt unassisted in the past five days.
The clue was in the name: Grit was always going to be embarrassing.
The clue was in that muscly, perky woman running the show. She was skipping and jumping and darting about the gasping masses and shouting encouragement into her Madonna microphone.
"Great guys, we've warmed up!" she said.
We were two minutes in and my heart was at 170. Just 28 minutes to go.
I'm someone who jogs most days and boasts to his friends that he's reasonably fit.
But a visit to a Les Mills gym class was a different matter.
In two minutes she'd found me out, quivering pathetically at the bottom of another tricep push up, the sweat beading and dripping off my brows. I do not squat-lunge with grace.
What is extraordinary about it all is that people pay for this. Many people. People with beautiful bodies and perfect gym clothes. The place still reminds me of a scene-y nightclub.
I'd been to a Les Mills class once before, but it wasn't at Les Mills. It was in Harlem in New York, where the singleted gym bunnies comfortably squat station wagons and a scrawny kid from Christchurch feels very un-muscly indeed.
A Kiwi friend in Toronto does Les Mills classes there as well. He's a shy guy and too polite to correct the instructor when she pronounces Les Mills a la Jean Valjean.
Inside tip for gym newbies: Les Mills is the former track and field athlete and mayor and the name of an international health and fitness company. Les Mis is a Victor Hugo musical.
It's a hard-out lifestyle for those who subscribe and a very good reminder when the dollar is high that we're capable of exporting more than milk and cheese.
• Jack Tame is on Newstalk ZB Saturdays, 9am-midday.