Adam Keighran got a rude awakening when his doctor bet him $100,000 that he wouldn’t live to his 40th birthday.

At 291 pounds, he’d been diagnosed with high blood pressure and gout, and his doctor told him he ‘looked pregnant’.

“Quite obviously this stinging assessment really struck a note,” Keighran told Men’s Health.

He’d spent most of his twenties indulging in unhealthy habits.

He traded playing sports for watching them on television and his game-day meals always consisted of pub food with a side of a beer.

Not only was Keighran a heavy drinker throughout his twenties, he was also a heavy smoker.

“I was working in the wine tasting and wine sales industry and my hours were flexible, which enabled a very unhealthy lifestyle that included late nights and late mornings,” said the Sydney, Australia native.

But, that all changed in September 2010.

Coincidentally, just as his doctor warned him that his unhealthy lifestyle was costing him years off his life, he discovered a charity called The Miracle Babies Foundation, an organization dedicated to supporting premature newborns and their families.

Keighran himself was born at just 27 weeks.

“I started reading up on the babies that did not survive their premature start to life, and also those that had survived, but continued to suffer from massive health issues,” he remembered.

“It really sunk in that I had been super lucky. Not only did I survive, but I suffered zero bad health issues except for the self-induced ones.”

Overcome with guilt, Keighran’s newfound awareness inspired him to ditch his unhealthy habits and transform his life, once and for all.

“I felt like I owed it to both myself and my family to turn my life around,” he said.

Lacking the courage and money to join a gym or to sign up for a food delivery system, Keighran immersed himself in nutritional science.

He started by counting his calories and slowly began exercising by incorporating a few days of riding his stationary bike and walking into his new routine.

Whether it was losing an extra pound or increasing his jogging distance, Keighran made a point of celebrating small victories every week.

“It was super motivating to see these things improve,” he said. “Everything worked together.”

It wasn’t long before he met his weight loss goal, losing a total of 109 pounds.

Motivated by his achievement, he decided he wanted to help others achieve the same success and became a personal trainer.

For Keighran, being held accountable was paramount to his success.

“I talk to my current clients a lot about having an ‘accountability guy,” he said. “Someone that can dish out the tough love but also nurture you through the tough times.”

Keighran decided that social media was going be his ‘accountability guy’ and began sharing his journey online.

It was hard at first to share what he called his “fat photos” with the world and to cope with some of the negative comments here and there, but instead of letting it get the best of him, he used it as motivation to keep pushing forward.

“That shift in mentality was crucial,” said Keighran.

Today, he is happier than he’s ever been.  “I’m proud of my life. I’m proud of who I have become,” said Keighran.  

“I found a lifelong love for running which has taken me to amazing places around the world and allowed me to meet some amazing people, too.”