The Scarlets No.8 weighed nearly 21 stone when he was signed by the Welsh region, who recognised his potential.
Morgan was made to drag sleds around the Parc y Scarlets and he wore weight vests on the running machine, breathing only through a snorkel.
Two-and-a-half years later, Morgan is 18st 3lb, a capped international and pressing to make his first Test start against Italy in Rome.
"It was great the Scarlets took a chance on me but getting fit was crucial. When I first went down there I was 132.5kg (20st 8lb). That's quite big," Morgan said.
"It took two-and-a-half years of hard work, dragging sleds around the stadium, wearing a snorkel on a running machine to get me into condition.
"I had no idea what food was good and what was bad. At the time I was working on a building site and basically eating whatever I wanted.
"Diet is such a crucial part of the game that I had to adjust that as well as doing the extra training. I've gone from being completely part time to being full time."
The 22-year-old has enjoyed an unconventional rise to the top, developing outside of the now routine academy system having slipped through the net as a youngster.
Morgan takes some responsibility for that, recalling one occasion when he injured himself on the morning of a Gloucestershire county trial by falling off his micro-scooter.
After stints with Dursley, Cinderford, Merthyr Tydfil and the Cardiff Blues Under-20s, Morgan was signed by the Scarlets and almost immediately found himself on the international radar.
If Warren Gatland had had his way, Morgan would have made his Test debut for Wales last week after qualifying on residency grounds.
Morgan was initially in a muddle and turned down a chance to play for the England Saxons - but then realised that he could not, in all conscience, represent Wales.
"At the time when I was asked to play for the Saxons I had so many people telling me what I should and shouldn't be doing that I couldn't think for myself," said Morgan.
"The easiest thing for me was just to say 'I need some more time' and put everyone off.
"As soon as everyone else had shut up and let me think for myself it was really clear and it was just about wanting to play for my country.
"It didn't matter about Wales because I'm not Welsh, I'm English.
"Playing for my country is about wanting to play for England and really be part of that.
"To be able to come onto that pitch last weekend is something I'll treasure for the rest of my life."
Morgan made an immediate impact off the bench on his Test debut against Scotland last week.
With Sergio Parisse waiting in Rome, England must decide whether to stick with the more experienced workhorse in Phil Dowson or opt for Morgan's more explosive qualities.
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