By Stuart Hughes
BBC Sport in Athens
Marlon Shirley gives me a hearty slap on the back as I stand, panting and sweating, at the end of the running track.
"That was impressive," he says. "You run a lot better than I thought you would."
Hughes (right) discovers a little too late that Shirley can run the 100m in just 10.97secs
I suspect he is humouring me.
The American track and field athlete won gold and silver medals in the Sydney Paralympics.
With a personal best over 100m of 10.97 seconds, he is the fastest amputee in the world.
Shirley is putting me through my paces. I clearly have much to learn.
Like the American, I too am a below knee amputee. I lost my right foot last year in a landmine explosion in Northern Iraq.
"Fast," however, is not an adjective I have ever used to describe myself - even when I had two feet.
For Marlon, however, the key to Paralympic success can be found at the other end of the body.
"Only about 40% of the preparation is physical," he says. "The other 60% is mental.
"The odds are stacked against you and success comes from knowing completely that this is what you want to do."
The odds were certainly stacked against Shirley in the early years of his life.
From the age of three, he was forced to survive on the streets of Las Vegas after being abandoned by his mother.
He had already suffered poverty and abuse when, at the age of five, his left foot was severed when he fell under a lawn mower while living in an orphanage.
Although nature provided the raw materials for Shirley's athletic prowess, technology has also played a big part in putting him within striking distance of the times achieved by able-bodied sprinters.
He uses a high-tech carbon fibre prosthesis aptly named 'The Cheetah'.
"Carbon fibre is stronger than cement but it can store and return energy," he explains.
"My leg is the prosthetic equivalent of a Formula One car. Yours is more like a Mini; it'll get you to where you want to go, just not as quickly."
Shirley hopes his state-of-the-art prosthesis will propel him to gold medal glory in the 100m, 200m, 4 x 400m relay and long jump at the Athens Paralympics.
As he heads off to continue his final preparations, he offers me a few parting tips.
"Keep your head up a bit more and focus on your arms - because wherever your arms go, your legs will follow," he says. "And get a new leg - unless you want to play golf!"