G’day from Australia! I should be having the time of my life on our trip, but I’m feeling a bit overheated in my too-tight trousers with their 44in waist. Plus, there’s something that’s really playing on my mind.

A few days ago we went to a huge water park and I couldn’t wait to have a go on the vertical flume. As I flew out of the chute and plunged into the pool below – where my wife, Charley, and a group of our friends were waiting – a great wave went up, pushing them backwards and showering anyone near the bottom of the flume.

There were shrieks of laughter from everyone… except the lifeguard, who peered down from her seat. ‘Excuse me, sir, how much do you weigh?’ she demanded. For the first time, I saw the sign that stated there was an 18st limit. ‘Er, 18st?’ I said, knowing I was more like 22st. Her eyes narrowed with suspicion as I waded off towards the side, laughing it off and trying not to let the rising flush of shame show on my face.

And now here I am, best man at my friend Will’s wedding, sweating in the Brisbane heat with my trousers and waistcoat feeling tighter and more uncomfortable as the day goes on. Although it’s a brilliant do, I just can’t get the stern disapproval of the lifeguard out of my mind.

It’s been a month since we got back from our holiday in Australia, and Charley and I are both unhappy with the way we look in the photos. I started gaining weight in my teens. At 16, I got a part-time job as a waiter at a football stadium and we’d often have staff matches. Though I wanted to play up front, I knew I was too unfit to run up and down the pitch, so I always offered to go in goal.

Then I met Charley and we moved in together. We were so happy in our lives as a couple that we didn’t really notice the weight creeping on. We enjoyed cosy nights in with takeaway pizzas, or pasta dinners made with shop-bought sauces and lots of cheese, followed by ice cream. And in my case, my weight was beginning to affect my health. I’d developed high blood pressure as well as shooting back pain that left me in agony from just walking to the local shop.

A couple of weeks ago, I started a calorie-counting diet half-heartedly. Then I lost my motivation and quickly regained the pounds. But just when I was starting to think losing weight might be impossible, chance intervened.

I was at work behind the till in our local supermarket earlier today, when a customer came in to ask if I minded her putting up some flyers on the noticeboard. She introduced herself as a local Slimming World Consultant. As we got chatting, she mentioned she’d just opened up a new group in our part of Leicester. As soon as I got home, I asked Charley if she’d ever thought about us joining Slimming World together and told her about the Consultant coming into the shop. Maybe this could help both of us to feel a bit happier about ourselves…

Today I went to my first Slimming World group. Even with Charley by my side, my nerves were jangling. As we walked in, I spotted another man was there. We hit it off immediately, joking with each other about who’d lose weight the quickest, and I felt an instant sense of relief. He didn’t seem embarrassed about being there, so maybe I’d been wrong to think people would judge me?

That feeling of relief continued to grow as I settled in and listened to the other members sharing their experiences. I had no idea that other people struggled with exactly the same things as I did, like the woman who said her biggest challenge was wanting to eat sweets late at night. Someone had a great idea: ‘Make some low Syn sugar-free jelly and eat that instead of sweets,’ she said. Well, that didn’t sound so bad – I like jelly. After loads more tips like that, I went home inspired and ready to take on the challenge.

May 2016: 20st 7½lbs

It’s been three weeks since I started Food Optimising and I’m already feeling so different. Charley and I got stuck in straight away, planning a week’s worth of meals and snacks, and only buying what we needed.

Now, instead of buying a sandwich, crisps and fizzy drink for lunch at work, I’m taking in my own crustless quiche or omelette wedges with lots of Speed Food salad. Our dinners have got more exciting, too. We recently tried the Slimming World burger in a bowl recipe with a delicious low Syn mustard sauce, rice and vegetables. And I’ve discovered another epic Food Optimising meal – cowboy pie.

My first weigh-in was a moment of glory. I’d lost 12lbs in a week! And as of this week I’m now a whole 1st 5½lbs lighter. Charley’s doing well, too – she’s already lost almost half a stone – and we’re both feeling really optimistic.

I’ve just got in from the gym at my local leisure centre. I’ve been going for a little while now and I’m starting to get the hang of it. On my first visit, I felt really awkward exercising among all the lean, muscly people. Then I caught sight of myself in the mirror – I’d already lost a few stone and could see that I was looking trimmer and healthier than I had in years. What’s more, I was determined to get even fitter.

Over the last few weeks, I’ve got into a healthy new rhythm: group, planning Food Optimising meals with Charley, and a few sessions at the gym. After that first visit, I quickly realised it didn’t matter if I didn’t have the perfect physique. No one was there to judge me – everyone was focused on their own goals. I’ve recently started using the cross trainer and rowing machine, and my breathing and endurance are really improving.

Just the other day, one of the gym staff joked: ‘You’ll be getting a job as a personal trainer before long.’ My body shape has changed so much, it’s not just me who’s noticing. Since then I’ve really been thinking about what he said and, actually, that sounds like a great job. So I’ve asked another staff member, who also goes to my Slimming World group, to let me know if a job ever comes up. Me, working in a leisure centre? That would have seemed impossible earlier this year. Now all I can do is keep building up my fitness and wait for my chance.

June 2017: 15st 10lbs

I’m at the water park with my two daughters. Lara-Hope is holding my left hand and Eva-Louise is grasping hold of my right. As Lara-Hope yells, ‘Come on Daddy, jump!’, the three of us throw ourselves into the swimming pool, sending up a splash.

It’s only 17 months since my embarrassing moment in that Australian water park and I feel like a new man! I got down to my target of 15st 13lbs in February and I’ve stayed around that weight ever since. Now, this dad is happy to take off his shirt and stroll around the water park with them, splashing around without worrying what other people are thinking.

I finally got the news I’d been waiting for: a position had been advertised for a lifeguard at the leisure centre. I had to laugh at first – without the actions of one particular lifeguard I’m not sure I’d ever have joined Slimming World, and if I hadn’t lost weight, I certainly would never have applied for the job.

I was thrilled to leave behind the world of retail, where I sat down for most of the day, and start training to do a more active job. I qualified as a lifeguard and started my new career full of enthusiasm.

July 2018: 15st 2lbs

I’ve only got a few more pounds to go to reach my new target of 14st 13lbs. Things have also progressed really well at work – I’m now a relief duty manager at the leisure centre and spend most of my days at the poolside. While looking better, being slimmer, wearing stylish shirts and 34in-waist trousers is also great, what matters most is giving my family a husband and dad that they’re proud of. That means more to me than anything else.

*Weight loss will vary due to your individual circumstances and how much weight you have to lose.