Muscly Jack Moore, 21, was dozing in a park with girlfriend Vicky Clarke when the tyres of the two-ton vehicle rolled across them.
Jack suffered horrendous internal injuries including broken ribs, a collapsed lung and liver damage.
But medics said the keep-fit fan – who turned to exercise and diet at 17 after hitting an obese 16st – could have been killed had it not been for his ripped washboard stomach.
Jack, whose six-pack was cut away to be replaced with an 8in scar and tyre tread mark, said: "The doctors said I was lucky I had more muscle otherwise I would probably have suffered more injuries.
“They said I was very healthy and that was also a big factor in my recovery.”
Jack and Vicky, 19, had just cuddled down on the grass beside a river in Earlham Park, Norwich, and shut their eyes when horror struck in June 2017.
The Toyota Hilux, which was going round emptying litter bins, went over both of them as onlookers screamed.
Jack recalled: "I opened my eyes and the truck was about a foot away from my head. I had no time to react and I just had to watch it happen.
"The front wheel crunched over my stomach which was really mentally distressing. It was the last thing I expected to happen and I think adrenaline kicked in so I did not feel the pain immediately.
"Then it drove over Vicky, stopped on her and started to reverse. I pulled myself back out from underneath it before it could run over me again.
"Then my stomach felt extremely painful and I knew something was seriously wrong with my body.
"I pulled up my t-shirt to look at it and it was really deformed and disfugured. My belly button was not in the centre anymore, it had been pushed off to the left.
"The thread details of the tyre were etched into my skin and the right side of my stomach was very red.
"Then the pain really kicked in. I tried to scream but my lung was punctured so I couldn't really do it.
"A little girl was the first person who rushed over to me, bless her heart, followed by her dad.
"Then about 10 people were around me, telling me to breathe and stay conscious. They were asking me what my name was and what day it was.
"It was difficult to speak and I just wanted to curl up in a ball alone with the pain but the people around me would not let me move.
"I'm lucky they were there because I probably would have lost even more blood internally if I had moved.
"Someone had called an ambulance and although it felt like an eternity waiting on the grass, it was actually really quick, we were lucky that the hospital was just one quarter of a mile away.
"The truck had punctured my lung, tore my kidney in two places, tore my liver, broke two ribs and I lost one litre of blood through internal bleeding.
"I lost so much blood that I started slipping in and out of consiousness.
"I remember the police arriving and a police woman standing over me, blocking the sun from my eyes.
"And I vaguely remember the ambulance arriving and the paramedics giving me an epidural and gas in the park before I passed out."
Jack was rushed to hospital for emergency life-saving treatment.
Jack said: "My next clear memory is waking up in a hospital bed. My stomach was extremely painful. I pulled back the covers and saw a huge scar running from under my nipple to my groin.
"I had tubes all over me with about six cannulas in just one hand. I had a big needle in my spine for the epidural and I had another tube coming out of my arm.
"I panicked. I did not know what happened. Was my partner ok? My mum was by my bed and she told me Vicky had been hit but she was alive.
"I think I was pretty out of it with all the painkillers but then it all started flooding back to me like a dream after you've just woken up."
Jack, who is being represented by personal injury specialist Slater and Gordon in a civil case, recovered after a hospital stay but was left with problems including not being able to use the loo properly.
He was also diagnosed with PTSD.
He said: "I still have abdominal pain and I was diagnosed with PTSD. Recovering psychologically has been more difficult than the physical aspects.
"I still get flashbacks of the moment I saw the wheel on my right side and watched as it drove over me.
"It was really traumatic. The park was a place where I always felt safe before. I've gone there for years walking my dog and there are always families and children there.
"It’s really knocked my confidence but I'm determined to get better again. I feel lucky to be alive and I hope that I can heal.”
Vicky suffered broken vertebrae, a broken collarbone and a fractured sternum in the horror crush.
She was admitted to hospital for treatment alongside Jack but she has since also been released.
Samantha Williams, a personal injury specialist at Slater and Gordon law firm who is representing Mr Moore in a civil case, said the accident will have a long lasting effect on her client.
She said: “Mr Moore has gone from being a fit and healthy young man with his life ahead of him to somebody who struggles to do the most basic activities without being in pain.
"Along with the horrific physical scars, he may never be able to erase the memory of the large vehicle driving over him.
"He and his girlfriend were lying in an open space, clearly visible to everyone around them, yet the driver of this vehicle failed to see them.
“It’s vital that lessons are learnt from this awful accident.”
The truck’s driver was fined £195 for careless driving and sacked by its operators, facilities management company Norse.
A spokesperson for Norse facilities management company said: "We referred this matter to our insurers shortly after the incident happened.
"Discussions between the two sides involved are underway with the intention of reaching an agreed settlement.
"The Health and Safety Executive (HSE) concluded driver inattention was the principal cause of the accident.
"The driver concerned was dismissed and the HSE acknowledged robust steps had been taken by our company in light of the incident and has told us no further action is planned against us.”