Aged just 15-years-old, Nathan Hewitt weighed 23 stone but, when he was turned away from a roller coaster ride at Alton Towers because the safety bar wouldn't fit over his stomach, the teen decided to make a change.
He explained: "I knew at that moment I had to change my life for good. My weight was making me miserable."
After burning off nearly half his weight, the 23-year-old now wants to help other obese children in his home town of Merthyr Tydfil, south Wales.
Thanks to £6,000 Young Entrepreneur’s Business Grant from the Welsh government, the inspirational young man has set up his own fitness firm.
And he believes that, having been obese himself, he will be able to help overweight children find the self-belief they need to make a positive change to their lives:
"I’ve been there, I know how it feels to be massive. You only have to look at my old photographs to see I was huge.
"A lot of obese children don’t think they can make the changes they need to lose weight but I’m there to show them they can."
Watch his Weight Loss Experiment video below:
On his website, at TryThisForSize.com, Nathan offers free advice on weight loss and tips on tightening loose skin after a diet.
He explains: "Today my life is completely different. It's been nearly 10 years since I was obese and unhappy.
"I want you to know that you can make changes in your life. I had to do it without the assistance of a professional. But you can take advantage of some of the free stuff I offer here, that will help you on your goals."
Are you inspired?