Lawrence Okoye has revealed he's enjoying the challenge of making it as an NFL professional after wrapping up his first ever rookie training camp.
The 21-year-old signed a free agent deal with Super Bowl runners-up San Francisco 49ers this summer, and has spent the past few weeks with the team.
It's a steep learning curve, but the former-Olympic discus finalist insists the scale of the challenge hasn't put him off.
"It's the hardest thing I've ever done, I'm under no illusions," Okoye told Shortlist magazine. "But other guys have made the transition before.
Okoye is looking to make the team as a defensive lineman, with his size, power and explosiveness a valued commodity in the NFL.
His discus training gave him a base to work from, but Okoye admits the 49ers' workouts have been a step-up.
"The two things are worlds apart," continued Okoye. "But there is crossover in terms of the work I do in the weights room where - for the past couple of years in particular - the objective has been to build size, strength and, most importantly, explosive power.
"Right now, my training time is spent between specific position drills, conditioning and weight training.
"It's different each day, but the circuit stuff designed to improve my anaerobic fitness is the real killer."
Okoye spent time playing rugby before turning hand to the discus, and once recorded a blisteringly quick 100m personal best time of 10.95 seconds.
At 22st, he concedes some of that quickness has evaporated, but his NFL position is all about explosive power over short distances - the aim being to get to the quarterback as quickly as possible.
That requires study though - NFL playbooks are notoriously complex, riddled with codewords, misdirection plays and vernacular unfamiliar to a man more used to the world of Olympic-level discus.
"It's going to be tough to learn everything from the defensive playbook to the positional responsibilities of our defensive scheme from scratch," continued the 21-year-old.
"But I look forward to it. I've always liked my studies, and we had to sit a sort of IQ test before the draft. I think I did OK in that; I'd be interested to see my score."
The 49ers prospect covered a range of topics in the interview - from the fittest athlete he's trained with (Mo Farah) to his eating habits (five small meals a day) to his music tastes (south London grime).
You can read the full interview here.