It was a lazy Sunday afternoon in front of a movie that convinced Dylan Dunn he needed to change his life. That he needed to return to what he loves. That he needed to start riding horses again.

Dunn is the son of famous jockey Dwayne and grew up besotted by horse racing, inspiring him to take up a riding career that started with a bang.

In 2016 alone, the young jockey was crowned Melbourne’s best apprentice, won Abu Dhabi’s Apprentice World Championship Final and even saluted on board a horse owned by the Queen – her first Australian winner.

But at 178 centimetres tall, Dunn was always battling his weight, resorting to unhealthy measures to stay light enough to accept most of the rides he was offered.

The process of losing big amounts of weight extremely quickly is called wasting – and it left Dunn sick. He got pneumonia in 2015 and glandular fever in 2017 and, ultimately, fed up, decided to retire from riding.

That was until he re-watched the 1983 movie Phar Lap.

“I was watching Phar Lap for the first time in five years,” Dunn said.

“I was just at home on a Sunday, with my missus – she had never seen it before.

“It was just the adrenalin and the emotion that you get out of race riding really coming through.

“I sort of thought to myself then … ‘I need to give it another crack, I miss that too much and I’d love to ride against dad again before he retires’.

“I just thought that while I’m young, I may as well give it another crack, because there is no point getting to 40, 50, and going ‘I should have had another crack’.”

Dunn rides the Queen’s horse, Bold Sniper, in his previous high-flying career. Photo: Getty

Dunn’s first port of call was to see a dietician and work out how he could maintain a weight of about 57 kilograms in a healthy manner.

He had already been encouraged by maintaining a stable 62 kilograms for six months of what became 20 months away from racing. That time was largely spent working as an expert on Racing Victoria’s TV channel, racing.com.

“She [the dietician] was pretty confident that the weight would come off if I stuck to a diet and I did. I got down to about 58.5 kilograms naturally on that diet,” he said.

“Coming back to race riding has given me that little extra bit of fitness, too.

“I’ve been able to ride at 57 kilograms fairly comfortable, and could ride at a minimum of 56 kilograms … but I’m feeling a lot better within myself.

“I’ve had to turn down other opportunities because of weight restrictions, but that’s unfortunately the way it’s going to have to be if I want a lifetime in the saddle.

“My old diet was all about the short-term but now my nutrition is better and I think it is helping me stay in a better frame of mind.”

Dunn is also “working out every day”. His strict diet and fitness regime means the unhealthy wasting habits are gone.

After his retirement, Dunn told The New Daily about the many ways he would shed weight quickly, including driving to the races in summer with the heaters on full blast and wearing “a plastic sauna suit, ski pants, two skivvies and jackets”, something that could help him lose “one to two kilos” just hours before taking a ride.

“Sweating in saunas, baths, cars, running in full-length wetsuits – I’ve done it all,” he said.

Dunn (right), in his role as racing.com expert, interviews his father, Dwayne. Photo: Getty

Despite his glittering CV, Dunn’s riding career resumed in country Victoria. Since starting back in September, he has ridden winners at Tatura, Donald, Hamilton, Echuca, Bendigo and Yarra Valley.

His impressive return was marked by being offered the ride on Jungle Edge in the Group 1 Manikato Stakes in October.

Dunn finished 10th in that race – but the ride served to reinforce that a comeback was the right move.

“Getting that Group 1 win next to my name is something … I don’t think I would be able to leave racing until I’ve got that next to my name,” he said.

“Riding against my dad certainly is a big goal, too.

“And I would also love to ride overseas if I got the opportunity.”

They are big goals but Dunn’s determination shines through in an extended discussion.

His break has left him revitalised, motivated and hungry for success.

And it all started from a film.