“The stand-out thing, for me, was missing the team environment and just training on your own, the early mornings, guys preparing for matches and you couldn’t be further from that, so that was the most difficult part,” he said.
Watching Dublin claim Allianz league, Leinster, and All-Ireland titles in his absence in 2015 can’t have helped.
And he turned 30 last September, so nobody would have held it against the dynamic Templeogue Synge Street attacker if the’d simply hung up his boots, after that injury the previous March.
He’d already achieved more than most, having been on the field of play at the end of both the 2011 and 2013 All-Ireland final wins.
Throw in his personal highlight — that goal smashed in off the crossbar against Kerry, late in the epic 2013 semi-final — and his scrapbook virtually bulged.
“But all I’ve ever wanted to do, since I’ve started playing for Dublin, is to be on the pitch, playing the matches,” said O’Gara, cutting to the nub of the issue.
So he put himself through those 12 torturous months of recovery, and eventually came out the other end, last March, playing half a challenge game for Dublin against Ballyboden St Enda’s.
It was a low-key warm-up for ’Boden, before the AIB All-Ireland club final ,but it felt like the final itself for O’Gara.
Fast forward another five months, and, with less that half-an-hour of Championship game time behind him, he popped up to annoy Kerry again, with the injury-time score that put Dublin one up in their two-point semi-final win.
“In that exact moment, kicking a score like that, you’re not really thinking about much, but, on reflection, afterwards, it certainly was very satisfying,” said O’Gara.
“You go through all the dark days with a cruciate, rehabbing and training on your own, so, yeah, I had a good, big smile on my face after that Kerry game.”
Like every other Dublin player on the current panel, it’s All-Ireland medals that O’Gara is after and playing some part in a win today is what he craves.
“Obviously, last season, I missed the Championship and it was very disappointing, but I spent enough time over that period being disappointed. It’s a new year, another final opportunity, I’m just excited. I’m happy to be back around the lads, to be involved.
“This is exactly where I wanted to be, this time last year when I was sitting in the stands watching the final with Kerry. I badly wanted to be in this position again, hopefully being able to contribute on the pitch, from the start or when called upon. Whatever I can do, I’m delighted to do it.”
O’Gara featured in all but one of Dublin’s Championship games in 2013, contributing 2-4, and adding another 1-6 in 2014, before the curse of the cruciate struck.
A scuffed kick and miserable wide, when brought on against Mayo 13 days ago, could be forgiven and summed up a difficult afternoon all round for the Dubs.
“It was frustration, disappointment with the team performance, and within, that you look at yourself first and foremost and I was definitely disappointed with my own contribution,” he said.
“Just the standards that I set for myself, in terms of work rate and that, I wasn’t best-pleased and I think a lot of the guys individually felt the same.
“Then, obviously it’s a bit of relief that you have the chance to put things right.
“You don’t always get that second chance, after games when you don’t perform.”
It’s a chance, he says, Dublin are determined to take.
“That work rate, that intensity, just the basics, the fundamentals, they’re something we’re going to have to do and make sure we bring to it,” he said.
“We can talk these things to death, but when the ref blows the whistle and we have to go out and actually work hard, then it’s time to deliver that intensity.”