"Indescribable" is the best way she can describe it, Síofra Cléirigh-Buttner casting her mind back to a blissful weekend in April when everything clicked, a moment she can't quite capture in words.
There she was, this diminutive 21-year-old from Dublin, racing in front of almost 50,000 fans at the Penn Relays in Philadelphia. After anchoring her college to victory for the third time in three days, Cléirigh-Buttner was given the athlete-of-the-meet award, high praise at one of America's most prestigious track meetings, an event that featured a raft of Olympic medallists.
To win as she did, though, Cléirigh-Buttner had to spend a long time losing.
Rewind for a moment, back to a time when victory was a constant companion. Cléirigh-Buttner grew up smaller in stature but a class above her peers in Ireland. She breezed through her schools' career without a rival laying a glove on her in races, outdated records running for cover whenever she toed the line.
So when she arrived at that all-important decision in sixth year, an awareness dawned that she had outgrown this particular pond.
Like so many Irish greats - Sonia O'Sullivan, Ronnie Delany and Marcus O'Sullivan, to name just a few - she accepted a scholarship to Villanova University, packing her bags for Pennsylvania and willingly stepping down to the bottom rung of the ladder.
Training, she knew, was primarily a science, but racing an art, so the only way to master that craft was to serve her apprenticeship with the best.
"When I was back home, I could run fast and time trial, but it's hard to learn tactics when you're out the front," she says. "I had to learn how to be surrounded by others in races."
No textbook can teach you how to run calmly in a suffocating cluster of athletes, and nor will it tell you whether it's better to kill your rivals with a sudden late attack or to slowly squeeze the life out of them early.
That must be learned the hard way, and in her first year at Villanova coach Gina Procaccio sat her Irish recruit down for a lecture in racing 101. She pored over footage, showing how Cléirigh-Buttner reacted to every move in her races, a rookie mistake and a fatal waste of energy.
"She taught me how to relax and not respond until it really matters," says Cléirigh-Buttner. "That's what really matters in the last 250 metres - who is most relaxed and composed."
The system she entered, the NCAA, is littered with more broken dreams than success stories for Irish athletes, but Cléirigh-Buttner has only seen the up-side.
She hasn't been run into the ground, despite the many cautionary tales. Instead she has been kept on a steady volume of 50 miles a week in winter and 40 miles in summer, the major gains made through strength and conditioning sessions in the gym and a weekly technical workout with Villanova's sprints coach.
And as for being homesick? "I never felt it," says Cléirigh-Buttner. "Perhaps I'm lucky, but if you really want to make it, you can't dwell on that. You have to make sacrifices. Even outside of athletics, the US has so many more options than at home."
Last year she lowered her 800m best to 2:01.98, within sight of the Irish record of 2:00.58, and ahead of the European U-23 Championships, which start today in Bydgoszcz, Poland, her best time ranks her second of the 25 competitors.
At this stage Cléirigh-Buttner is a veteran of international competition, and though there'll be no more than a couple thousand spectators watching when she takes to the track for her opening round this afternoon, pulling on a green vest will be all the motivation she needs.
"It's a privilege," she says. "I don't ever take it for granted. Running against the best girls in Europe gives you a different experience to what I faced in America, but this is a great opportunity."
The overwhelming favourite for gold is Iceland's Anita Hinriksdottir, who should win barring an accident, but Cléirigh-Buttner will feel confident of a medal if she can advance to Saturday evening's final.
"You always want to do as well as you can," she says. "You're running for yourself out there but also for your family, your team, your country."