A FEW years ago Jennie Gadsby didn’t even own a pair of trainers. The thought of joining a gym, she says, was as mortifying as doing karaoke in the nude.

Now she owns a gym, has climbed the Three Peaks and is currently training for her third 10k ‘mud run’. She runs two Weight Watchers groups, in Pudsey and Horsforth, and is a fitness expert for Weight Watchers UK, helping people who would never normally set foot in a gym to adopt a fitter, healthier lifestyle.

Jennie was size 24 when she joined Weight Watchers in 2007. By 2009 she had lost seven stone, and six dress sizes. But after losing the weight Jennie was lulled into the false sense of security that many slimmers know all too well, and she stopped going to slimming group meetings. Gradually, her weight started to creep back up.

"I don’t ever remember food and my body not being an issue. By my teens I'd become numb to fat jokes and remarks about my size," says Jennie, 33, of Pudsey. "I wasn't lazy, but I didn't have a particularly healthy lifestyle, and by my early 20s I felt I'd lost some of the best years of my life. I lacked the confidence to do things I wanted to do. I hated going shopping with friends, I'd tag along and stand outside changing-rooms, envious of them trying on cute outfits while I was in black trousers and smock tops.

"I tried diets and always failed, ending up fatter and more miserable than before. When a friend asked if I'd join Weight Watchers with her, I went along for morale support. At my first meeting I was horrified to find out I was almost double a healthy weight for my height. I was 22 and a size 24.

“I used an inhaler daily, I had pain in my ankles from the weight. I decided I wanted to change - my goal was to shop in Top Shop like my mates!

Adds Jennie: “Weight Watchers helped me feel better about myself. I learned about healthy eating, portion control and cooking from scratch. I followed the guidelines and found I was eating better, but without restrictions. As I lost weight, I gained confidence and when I reached my goal weight I decided I didn’t need to continue with the weekly meetings. But without that support and group therapy, I started putting weight back on again, so in 2013 I went back."

Now Jennie is back to her goal weight, and still goes to meetings. "It’s an hour of my life a week - if I can spend that hour keeping to a size 10 that’s a good enough reason to keep doing it,” she smiles.

After losing weight, Jennie discovered the benefits of regular exercise, and hasn’t looked back. “I’d never set foot in a gym. I used to say I hated gyms, but the truth was I was too embarrassed to go to one. It was like being asked to sing karaoke naked," says Jennie. "I felt very intimidated by gyms, I was too scared to give them a try.

"Then I started going for short walks, just 10 minutes round the block after tea a few times a week. I enjoyed it and started going a bit further. One day I walked past a leisure centre and it seemed quiet. I thought if there was no-one there to laugh at me, I’d give it a go, so I plucked up courage, and did the treadmill for a while. Then I tried a boxing class and within 10 minutes I was hooked. I joined other classes and found I really enjoyed being active. I discovered a new passion for exercise."

Jennie went on to take a personal training qualification over two years. “I worked in heritage management, so it was a total career change," she says. "When I qualified, friends asked me to help them get fit. They didn’t want to join gyms because, like I was, they felt intimidated.”

Five years ago Jennie set up a fitness studio in Pudsey called Set U Free. The aim, she says, is to help people who wouldn’t normally set foot in a gym feel “strong, confident, empowered and in control of lifestyle choices”.

“It’s for anyone who doesn’t feel comfortable with gym membership,” says Jennie. “The thought of going to a gym used to scare me because I thought they were for skinny people, full of body confidence, not for people like me. I had female friends who didn’t feel comfortable in gyms either.

“As a personal trainer, I loved helping people feel better about themselves. I wanted to extend that to a fitness studio environment. Set U Free is a friendly, welcoming, place where people can feel comfortable and get fit, with advice and support. Motivating people to make small, realistic changes can lead to a lifestyle change, and lifelong results. We have small group workouts, ladies’ classes and personal training. It’s a fun, manageable programme tailored for individual needs. We’re a little community; we support, inspire and motivate each other.”

As well as leading classes in the fitness studio, Jennie takes people out on challenges and charity fundraisers. Last year she helped raise nearly £11,000 for Yorkshire Cancer Research through a series of ventures, not least leading a group of 12 women of mixed ability on a climb of the National Three Peaks.

"It's wonderful to see people who would never have done anything like climbing a mountain in their life get so much pleasure from these challenges," says Jennie. "It's not a competition, we do it as a team. Our motto is: "Alone we're strong. Together we're stronger".

"In April I'm leading 19 ladies aged 27 to 76 (10 of them are in my WW meetings) on the Yorkshire Warrior, for Yorkshire Cancer Research. Last year I lost my dad to pancreatic cancer, so I like to support cancer charities. On April 21 I'm doing the 10k mud run in Harrogate, it's the third one we've done as a team."

Now Jennie has been awarded a Diamond Coach award by Weight Watchers UK, for her inspiration and dedication to her members."As I tell people, I'm active because I enjoy it, not because it's a chore," she says.

* Visit setufree.co.uk or call 07816 819 209. For more about Weight Watchers visit weightwatchers.com