Jack O'Connell knows just how quickly a footballer's fortunes can change.
Six years ago, after being signed by tomorrow's opponents Rotherham on loan, the Sheffield United defender made his professional debut as a second-half substitute against Exeter City. Five-and-a-half seasons later, he has blossomed into one of the Championship's most accomplished defenders whereas the player he replaced, Courtney Cameron, was last seen appearing for Coventry United in the Midland League Premier Division.
It is exactly that understanding, although there appears little danger of him needing it anytime soon, which has persuaded O'Connell to enroll on a sports science degree at college. But he still remembers the lessons he learned studying under Steve Evans, Paul Warne's predecessor, at New York Stadium.
"It was a wake-up call," O'Connell remembers. "On my debut, he just came into the dressing room and went loose on me, and I was just like ‘wow, this is mad’ because I thought I'd done okay.
"But it was good to get that taste of it so early on and it held me in good stead for the rest of my career.
"I didn’t get picked up until I was 17 so only had a year in the academy, then it was straight out into men’s football. I wasn’t one of those that was molly-coddled, I went to sixth form and stuff like that. But yes, it was a good taste of what it can really be like. There's no doubt about that."
O'Connell started his career with Litherland REMYCA, an amateur club in Merseyside, before being signed by Blackburn Rovers. That non-league grounding, combined with a sports-mad family, has served him well in the professional game with Brentford acquiring him for an undisclosed sum in 2015 before United came calling 12 months later. A member of the squad which lifted the League One title during Chris Wilder's first season in charge, O'Connell is expected to make his 117th appearance for United when they visit his former club this lunchtime.
"I’m from quite a physical background," he says. "My mum always used to have as running when we were kids, or out on our bikes. Brother was in the army, another one boxed in the RAF, so I’ve always had a physical background and I loved it. I've boxed a little bit myself but obviously nothing professional."
O'Connell's combative qualities could prove invaluable if, as seems likely, Rotherham start with Michael Smith up front in this South Yorkshire derby. The former Swindon Town and Portsmouth centre-forward, who stands six feet three inches tall, is among a number of threats United have identified in Paul Warne's team ahead of a fixture which could see them regain first place in the Championship table.
"He’s a handful," O'Connell admits. "I played against him at Swindon and he was a handful then so hopefully we can keep him quiet.
"We’re good at set-pieces, we’ve got three big centre-halves and two big strikers so we’re fine on those."
Despite preparing for the visit to Rotherham in fourth place, 15 above Warne's men, United's neighbours will actually enter the fixture in better form having taken seven points from their last five outings.
Despite collecting only five during the same period, O'Connell is adamant their performances since the last international break deserved greater returns.
"We’ve been playing well but not been picking up the results we wanted, which is why it’s really important after this international break that we change that now. There's still a long way to go yet, it’s just about being consistent, keep putting the performances in and hopefully the points will come. We've had a good start and we're still in a good situation."