When Simon Richardson saw a picture of himself last Christmas weighing close to 23st, he knew he needed to change his lifestyle.
So he plucked up the courage to join his local slimming group the following month and embarked on a strict diet and exercise regime.
And within just 20 weeks the 41-year-old lost an astonishing 10st and now feels fitter and healthier than ever before.
"Physically I feel great. I've been able to buy medium-sized clothes for a change rather then triple XL," joked Simon, who works as a team leader in a supermarket.
"I used to have terrible trouble with my knees, and as part of my job was stacking shelves it was sometimes difficult to myself back up after bending down.
"But now I don't have any problems like that."
Dad-of-one Simon, who lives in Hirwaun in the Cynon Valley, said he attempted Slimming World 10 years ago and lost an impressive seven-and-a-half stone.
But gradually over time, thanks to a diet of takeaways and other calorific foods, he piled the weight back on and more.
"I would be eating the wrong sort of stuff, things like crisps and chocolate," he added.
"I was just getting back into my old habits all over again."
He said the turning point came when he saw a picture of himself looking overweight.
"It was becoming a running joke in work that I'd start Slimming World back up again in January. It was like that for probably about three years," he said.
"I'd also had a major health scare when I developed sepsis after a holiday to Bali. They traced it back to an insect bite in the end, but I was in hospital for two-and-a-half weeks.
"I knew I needed to change my habits and be healthy again."
Within the first week of joining Hirwaun Slimming World, Simon said he lost an astonishing 16lbs.
From then on, after preparing healthy meals at home and avoiding foods with "syn" value, he lost an average of half a stone every single week.
Simon said he now cooks a range of meals from scratch, including quiches, healthy roast dinners and fish pies.
He also started walking from Hirwaun to Glynneath for work - a two-hour round trip - and cycling along the Cynon and Taff trails.
"I do have to do a double-take in the mirror sometimes," added Simon, who lost half of his weight during the lockdown period and now tips the scales at 12st 11lbs.
"One of my friends came into the supermarket who I hadn't seen for weeks and he didn't recognise me.
"A lot of people think I've had a band fitted because I lost the weight so quickly."
In February, Simon also had to contend with needing his appendix removed, which left him recovering for many weeks and set him back on his weight-loss journey.
He is now pledging to continue living and eating heathily.
