Greene needs history to keep repeating itself to keep his lifelong Olympic dream alive
For many Olympic hopefuls, the nagging self-doubt will generally focus on whether they can produce a time good enough to qualify for the main event.
In Darragh Greene's case, it is all about repeating what he has already done, but doing so when it matters most.
In the last year, the 23-year-old has swam under the Olympic qualifying time in both of his events, which has naturally given him a major boost ahead of next month's World Championships.
Greene now holds the Irish record for the 100-metre (59.92 seconds) and 200-metre (2:10.05) breast-stroke, while he became the first Irish man to break the one-minute mark in the shorter event.
"The way I look at it is, I have already done the time, I just need to do it a year out, but I obviously have that confidence," Greene told the Irish Independent. "I did the time last summer. That was in the 100-metre breast-stroke and then the 200-metre breast-stroke, I did just there at national trials.
"You can't really big it up because you are going for bigger things. If you let it be the be all and end all, you will never go beyond that.
"I have proved to myself that I can do it, so it's more of a thing of doing a personal best or a lifetime best and getting through the rounds. It's one of those things that you wonder if you are able to do it and then you only realise it when you do it."
The Longford native's reputation has been steadily on the rise since he switched his focus from sprinter to endurance swimmer.
This year is massive for Greene, who doesn't shy away from the fact that qualifying for the Olympics and fulfilling a life-long dream means everything to him.
There have been many sacrifices along the way, including deferring a year of his sports science and health degree. "A lot of people don't realise that it was a six-day training week," Greene explained.
"I'm up at six every morning, on the pool deck for seven and in the water at half-seven until around half-nine, depending on the session.
"Then after that it's either the gym or we see the physio and dieticians and stuff. We will train in the evening from three to half-five as well."
The change in training for endurance competition has also taken time to adjust to.
"It was a huge change for me," he admitted. "I used to be doing up to three kilometres per session and now I am doing up to five.
"Even when you drop the volume down for competition, I am only getting down to three kilometres, which is what I was used to.
"If you are a sprinter, you would need to be a bit bigger. It makes you more powerful but at the same time if you have more muscle, you have to bring it through the water. It's really just finding that balance with your events."
Growing up in Newtownforbes, GAA was a big part of Greene's youth, while he also played a bit of soccer with the Longford schoolboys.
The Olympic dream always burned strongest, however, and it wasn't long before he was putting all of his energy into securing a scholarship in Dublin.
A few years on, Greene lives on the national sports campus, a stone's throw from the pool, which is extremely handy, but can also feel quite claustrophobic.
"I try get out of the campus as much as possible. It's great to have it but at the same time, mentally, you need to get a break from it.
"Even just getting out and going down to the shops, whether that's going into the city or meeting friends, it's needed because you find yourself on the campus 24/7. I try get home to Longford whenever I can and just meet friends who aren't into swimming."
Greene is currently jetting around Europe, ramping up preparations for Swim Ireland's training camp in Japan, which will give everyone a taste of what to expect in Tokyo for next year's Olympics.
Next up for him is the World Championships in South Korea, which begin on July 12, and if Greene can clock up the kind of impressive times that he has already done, the sacrifices and countless early mornings will all have been worth it.