Conor O'Keeffe was used to being on his own. As an ultra runner, clocking up to 200 miles in one go, he'd had to get used to pushing through and looking out for himself.

As a Thai boxer, he'd won European gold as a teen, so he was able to fight things off, too. To keep the metaphor going, he'd scaled Kilimanjaro at just 17, so he was used to overcoming obstacles.

But it wasn't until one morning, when his Bluetooth headphones died 400 metres into a 30km run, that he was almost stopped in his tracks by something far more challenging: this own intrusive thoughts.

O'Keeffe shares the experience of coming to terms with years of heavy drinking, depression and anxiety in I'm Fine, RTÉ's newest documentary series that follows Lorcán McMullan, Ray Connellan, Hugh Mulligan and O'Keeffe as they speak about their struggles with mental health.

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When a head injury put an end to his shining Thai boxing career, O'Keeffe had to reckon with what had brought him to that point. "When I finished boxing, I really hit a point in my life where I absolutely had no real direction, which I now know is fine", he tells me over the phone. "It's perfectly fine not to have direction at some point."

"I needed something to focus on... and I never really found it."

"I was definitely quite manic at times", he adds, "where I would be on top of the world one minute and then the next minute fall off the edge of the earth and my mood would just drop."

Despite his clear success in sport and many hard-won accolades, O'Keeffe says he still wasn't finding the joy he expected from the sport. "I had this yearning to belong and I had this yearning to kind of be part of the be part of the group", he says. "I felt like a bit of an outsider because I felt a bit weird and I was a bit off centre as a child."

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Because of this, he turned more and more to "personas" he could perform for others, finding out what kind of person others wanted him to be, and being it. The cost of this, he says, was "not being true to myself". It was this impulse that kept him in Thai boxing two or three years too long, even when it wasn't making him happy anymore.

"I was clinging to the fact that it gave me an arena to belong to."

Years of drinking and partying passed, he says, during which he put little to no effort into finding what would make him happy. He fell into "self destruct mode", where "I didn't care about my health, I didn't care about my wellbeing, I didn't care about anything other than just getting through day to today and trying to have as much fun as I possibly can in the short term, not thinking too much about the long term".

It wasn't until he took up running – ultra running, no less – completing his first marathon and then an ultra race, with just seven weeks' training, that he found a route back to himself. That fateful morning, when he stepped out for his long run with only his dead headphones and his breath to keep him company, was the first time he'd listened to himself think for ages.

"I had this opportunity to talk to myself and this opportunity to be honest with myself in ways that I think I'd never been before, to take accountability for my life and where my life was and really show compassion to myself, forgive myself for certain things and be able to move on.

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"I'm not going to be able to change the beginning, but if I start where I am, I can change the ending."

Ultra running is one of the most solitary sports there is, and having gone from the competitiveness of boxing with others to just him, his runners and the road, he "realised that there was this drive within me to be honest and open on myself".

Running was his way of letting his own guard down, a challenge many of us struggle with when we have so many things to hide behind: work, exercise, traveling and accomplishments. What came up on those runs was sometimes "ugly" and "hard to digest", he says, but it was a kind of "truth serum", too.

"Through the endurance training, I developed what I call 'every day endurance' where I was able to transfer this comfortability with myself and flexibility in my own mind just into my every day. And so I wasn't really at the mercy of the outside world as much."

Now, O'Keeffe is passionate about sharing problems and vulnerability with others as he believes that once you do, it makes it easier for those around you to do the same.

"The thing about it is when you open yourself up to talk to people about issues or problems, you in turn opened the door for them to to share their own issues and problems", he says.

I'm Fine is exclusively on RTÉ Player and is sponsored by Electric Ireland. Electric Ireland is proud to continue to shine a light on mental health through it's long-term partnership with Pieta and Darkness Into Light and now through the I'm Fine series. During the darkest of times, we're Brighter Together.

*If you are affected by any of the issues raised in this article, you can contact; The Samaritans (phone 116123), or Pieta House (1800247247).