One of the lasting images from Ireland's World Cup campaign is Josh van der Flier's battered and bruised face following the quarter-final defeat to New Zealand.
He looked more like he had been in a boxing fight rather than rugby match as he embodied just how much the All Blacks had beaten up Ireland.
The physicality that was on show in Japan was off the charts at times as South Africa steamrolled all before them to be crowned champions.
The nature of Van der Flier's position means that he will always be in the thick of the action, and since returning to Leinster he has set about being better able to withstand that kind of physicality.
That in itself is a tricky challenge because although the easy solution would be to hit the gym hard and pile on the muscle mass, it's not quite as straightforward as that. What makes Van der Flier such an excellent operator is his huge engine, which allows him to get around the pitch and invariably get through a mountain of work.
By his own admission, putting on weight has always been an issue for the Wicklow native, but he knows that it is all about finding the right balance as he prepares for the physical challenges that lie ahead over the coming weeks in the Six Nations.
"I learned a lot in the World Cup around physicality, how physical the games were and my mental preparation," said Van der Flier.
"I would put more on the physical preparation. I would always mentally prepare or try and do a lot of work on... let's say we're doing some move, what I'm going to do for that, whereas I've probably put a bit more emphasis on mentally preparing for the physical side of it as well, and visualising myself making a dominant hit or poaching at the breakdown. It's probably something I focus on a bit more.
"The World Cup was probably the lightest I've been. Pre-season was pretty tough, I find it tough to keep my weight on. It was the lightest I'd been playing competitive matches at the World Cup in three or four seasons.
"It wasn't on purpose, but then I actually felt really good playing a bit lighter, felt a bit sharper.
"It was pretty tough training. It's always hard to eat, hard to get the food in, when you're doing fitness. It felt really good to be a couple of kilos lighter.
"It is getting that balance. You don't want to be slow and heavy, and you don't want to be too small.
"I try to get that out of my head because the back-rows I play with, like Rhys (Ruddock) and Jack Conan, are about 19kg heavier than me. Sometimes I feel like I should be up at that size. I've had a good few chats with Stuart (Lancaster) and Leo (Cullen) about it and they are happy with me at seven as long as I am quick around the place."
For all of the competition in the Ireland back-row, Van der Flier would appear to be a certain starter against Scotland in a fortnight. Not that the 26-year-old would ever take something like that for granted.
"There was some things I wanted to work on, I wanted to get a bit more ball carrying into my game," he explained. "I had a chat with Stuart. You might have seen it in some games last season or at the World Cup, I found myself on the edge quite a bit and not really getting that involved.
"Stuart told me to be more demanding of the ball and he was happy that you end up wide because the backs are gone in the middle in the rucks, and someone needs to be in the space.
"He was happy that I should be getting a bit more involved and get a few more carries under my belt. It was something I was definitely trying to work on.
"There's definitely, for me anyway, a feeling that if you play average it's not going to be good enough to keep your place."