I reckon there's a lesson in this for everyone; if you enjoy how you exercise, you'll want to keep it up. But John will take you to his gym only if there are safe, enjoyable weather conditions. The first trip I'm scheduled on is postponed because the weather gods throw a full-blown tantrum (ie, it's way too windy).
But the next day, it's just 16 knots, "perfect conditions", says John, who gives the green light for our group to go. I'm among a dozen locals and a German tourist, including a teacher, an IT guy, a freight-forwarding chick, an arborist, and a psychologist.
John checks we all do some physical activity. We don't need to be athletes, but doing more than just lifting the TV remote will help us hack this adventure. The trip is around six hours return.
He briefs us on safety, paddling technique and checks that our lifejackets fit tight. He then pairs us up for doubles kayaks and I'm put with another guide, Martin Draffin. He's got the steering pedals by his feet, he's in control, while I'm just more paddle power.
We kayak past a wharf, lighthouse, ferries, yachts and boats. I spot a stingray but, sadly, miss the penguins that sometimes steal the show. It takes 90 minutes of non-stop paddling to reach the island and my arms feel worked out, my hair is wind-whipped, my lips taste of sea salt and my digits look like I've been in the bath a tad too long.
Our group hauls the heavy kayaks up on to the island, then climbs the 600-year-old volcano that boasts a pohutukawa "forest" and a few quirky old baches.
The track, and sometimes stairs, are well made, smooth enough even for a pram, while on the sides of the path is a unique sight of black volcanic rocks.
Along the walk, John often stops our group for rests and to point out native plants, birds and to remind us to soak up the stunning views. The guy even raves about how beautifully the dappled light hits some trees.
When I reach the summit, I'm wowed. I take in the panorama of Auckland city, the Hauraki Gulf, dot-size boats and a toy-size harbour bridge. I see Auckland from a completely different perspective. It's perhaps her most magical outlook.
"How do you like my gym?" John asks.
"Incredible," I say.
We picnic before descending the volcano then have just enough energy to paddle back to Okahu Bay. It's been a buzz.
How much? $120 a person
Worth it? A great day out. Where else can you kayak to a volcano? Choose the night tour to see the city lit up after dark.
Try it: Fergs Kayaks, 12 Tamaki Drive, Okahu Bay, Auckland, www.fergskayaks.co.nz
Rating: 10/10