I like to walk. I'm good at it. I've done the MoonWalk marathon. Twice. So here I am, at the Rockliffe Hall hotel and spa near Darlington, thinking this is going to be my easiest Guardian assignment so far.

I've been asked to meet my instructor, Peter Bell, half an hour before the regular Nordic walking group arrives. He wants to assess me and run me through a few learn‑to drills. We've been lucky with the weather. It's a glorious sunny morning: not a cloud in the sky, crystal-cut fresh air and a sharp, refreshing breeze blowing from the north. I'm looking forward to this. It's perfect walking weather.

Peter is tall and trim. He hails from County Durham where he grew up in a small mining village but felt restricted and needed to move on. He joined the army and served with the Royal Artillery as a gun detachment commander: "I was the one who said, Fire. We used to blow up cardboard tanks."

He was posted all over the world but after seven years, decided to take up a career in rehabilitation fitness. Two years ago, Rockliffe Hall opened and they asked him to join them. "Everyone is walking wrong," he tells me, fixing me with a determined stare. "We're living in a slouch culture. Everyone's hunched over their computers, and then they stand up and walk with a slouch as well. Nordic walking is all about doing it right. It forces you to walk well without thinking about it. And you'll burn twice as many calories as normal walking. Right then, let's go round the back and have a play."

It's been a long time since I've been asked to go round the back for a play, and I'm up for it.

We start with a basic drag. I've been given two Nordic walking poles. These are different from normal walking poles in one respect – they have straps that force your hands into a more natural position.

"Conventional walking poles are no good," says Roger, with some passion. "They force people to lean forwards. That's putting unnecessary stress on your lower back. And people who walk with one stick are doing themselves terrible damage. People become one-side dominant and that leads to muscle waste on the neglected side, which leads to knee and back problems and hip replacements."

Movement, I learn, should come from the shoulder and it's interesting, once I've got the poles in my hands, what a difference it makes.

"Blimey," I say, after we complete the drag and pole-sticking drills. "The back of my arms hurt. What's that about?"

"That's your bingo wings," says Peter. "No offence. You're working all your upper body without knowing it. Nordic walking is amazing."

There's a trick to the last part of the drill. It's the propellant technique, the bit that "puts the spring in your step" as Peter likes to call it. You use the poles to push yourself forward and he's right, it makes you bounce. And that bounce takes all the stress away from your joints, from your ankles right up to your neck.

Peter's happy with my progress so we go off to meet the Nordic walking group I'll be going out with. They're all ladies. There is a regular man, called Roger, but he's not here today. "He likes to show off a bit," Peter tells me, in a quiet hush.

It's clear from the off that this is just as much about the social gathering as it is about the exercise.

"Nordic walking has changed my life," says Hilary, a bright-eyed lady who came to Darlington after the death of her husband. "I hid myself away," she tells me. "And then I came here."

She's become really good friends with one of the other ladies, Ann, and they've just got back from a skiing trip together. "Ann met a man," she whispers. "He was lovely. Got up early and gave us brownies."

We tackle a three-and-a-half-mile walk. The pace is brisk but manageable, and there's no doubt about it, with the poles it's a different experience. By the end I'm invigorated and I feel as if I've had a proper work-out. In fact, I'm aching.

"You've woken up your sleeping muscles," Peter tells me, smiling. "You're walking properly for the first time."

And I have to say, after a wonderful morning, I intend to walk properly for the rest of my life.

• Entry to the spa at Rockliffe Hall, Hurworth-on-Tees (01325 729999, rockliffehall.com, from £40) allows use of all its facilities, and all classes, including Nordic walking, available twice-weekly