At some point in him football career, a specialist told Kevin Doyle, he probably suffered a concussion but did not realise it - he might not have even understood the term at the time.
Had he been given time to rest and recover from the injury, it's likely he would not have had to retire, aged just 34, with the rest of his body still in working order.
"I was never 'officially' concussed my whole career until this year, when obviously I'd had bangs [earlier in my career] and been knocked out on the pitch where I would have been concussed. It wasn't a thing five or ten years ago," Doyle told Ryan Tubridy on the Late Late Show on Friday night.
Doyle called time on his career in late September following advice from a neurologist. The Ireland international was playing MLS at the time for Colorado Rapids. He had just suffered a concussion - his second one of the year - after an Ashley Cole clearance hit him on the head.
A year-and-a-half to two years ago, Doyle began feel "dazed" whenever he headed the ball. He thought it was a bit odd at the time but continued on.
To begin with, I didn't really correlate it with heading. It was like, come in after training and I wouldn't feel well. After a while I started to realise that every time I head the ball I'm not feeling great. When you're a player, if your muscles are feeling good, your legs are feeling good, you don't care about anything else.
Doyle managed the situation by not taking part in finishing drills in training; not heading the ball in training at all if he could manage it.
He got to the end of last season and then enjoyed three months off. He presumed that the issue would have been alleviated by the time he returned to training in January but the symptoms were still present.
Doyle soldiered on, still holding out hope of being part of the Ireland squad at next year's World Cup. He suffered his first concussion of the year towards the end of the MLS pre-season in February.
I shouldn't have got it a concussion from it, it was a simple collision with a goalkeeper. I had a bad concussion and I never had a bad concussion from a simple collision before. That worried me.
To be fair, in America, they're very good. Straight away: not allowed train, not allowed play; you go see a neurologist. I didn't tell him a word about my heading the ball issues because you know deep down that if you tell them those things, they're not going to let you play. I get through the year, I can manage that.
The Wexford man continued to have headaches following games, but they would clear up after a while. However, when he suffered the concussion in September, this time - following a discussion with his wife - he told the neurologist about the problems he was having after heading a ball.
Tests were undertaken and he was advised that he should retire from the game. He was told that if he continued, he might be fine. However, he was also told that he could get stuck with the symptoms of concussion should he continue playing.
You get stuck with headaches, you get stuck with feeling sick, you get stuck feeling a bit depressed, basically. You're like in a funk, they call it. You're not right. That was the prognosis, he said, that could happen.
After getting a second opinion, Doyle decided to retire, something he knows is the right decision.
"Jumping out of bed in the morning, it's annoying. Lads my age, I'm 34, usually have a sore hip, a sore knee; everywhere's perfect, which is a little annoying but it's very good, I can do whatever I want. I feel great."
Kevin Doyle reflects on the moment he finally realised he would have to retire due to persistent concussion problems #RTEsport pic.twitter.com/eoC5UpcwyN
— RTÉ Soccer (@RTEsoccer) November 10, 2017
