The record-breaking track star made the revelation in rugby player Tommy Bowe’s new documentary, The End Game, which tracks the last five months of his career to his retirement at the start of the summer.
It shows Bowe deciding to quit at the top of his game, at the age of 34, after speaking to top athletes about their own departures.
After recovering from injury following the 2012 London Olympics, O’Rourke said it hit her while she was driving from Cork to Dublin, two years later, that she had lost the hunger to compete.
A few days later, after consulting her coaches, she dropped the bombshell of retirement in her Irish Examiner newspaper column in 2014, and went away to a spa for a day.
She said: “It was a really odd experience, because people kept talking about me in the past tense, like I was dead.
“That sheer hunger you have to perform well just wasn’t there. My coaches said to walk away when you feel good and still love the sport.”
But she said she still has huge drive and ambition for life after athletics.
She said: “I had written a cookbook and signed up to do TV shows and I was doing some media work.
“For me to feel like I wrote the last chapter in my athletics career was really important.
“It helped me stroll out of it and walk out into the sunset and be happy with it.”
Derval said she is very cognisant that she is one of very few people to have performed at the very top of sport.
“Nothing I do will ever be the same, so I don’t try to replace it,” she said. “For me, definitely, having my daughter, I’ve never done anything greater than that, but you couldn’t possibly compare being a mum to going to the Olympic Games.
“It doesn’t mean they are not equally brilliant. They are just very different.”
In the documentary, Ireland soccer legend Paul McGrath said he surprised himself when he made the abrupt decision to hang up his boots, after a disastrous game for his last team, Sheffield United, before the end of his contract.
“I knew there was something wrong in that game,” he said. “I had never given the ball away so much.
“It was a strange decision, on one given day when I couldn’t kick straight. I said I don’t want to be remembered for somebody who is not a good player. I could have gone on until the end of the season.
“I went in and told them: ‘Thanks for everything, but I’m just not up to it anymore.’ ”
Bowe said he also felt like he had made the decision to go out on top.
“I know I could play for another year or two, but will I really enjoy not playing at the level I knew I used to be at?” he said.
He admitted it killed him not to be involved in the Six Nations while he was still playing rugby.
“You have to make the decision eventually,” Bowe said.