Along with her coach and father Patrick, she has devised a strategy for success that involves swimming over 80,000 miles a week.
As a medley specialist, who won 400m silver at last year's World Championships, Miley has to be world class at all the strokes if she is to be competitive in an event that includes defending Olympic champion Steph Rice, world champion Elizabeth Beisel and Spanish threat Mireia Belmonte Garcia.
And while she will also compete in the 200m medley and medley relay, Miley's signature event is up first - and will be decided on the very first day of the Games.
"I have got to stand on that block knowing that I have given everything that I could for that moment," she said.
"I've always believed that you work hard in training and just see where that takes you in competition.
"I don't want to be in this situation thinking that I hadn't done everything that I possibly could to prepare. I know this race and I've been swimming it for years. If I do it the best that I can, then we'll just have to see where that gets me.
"Every effort that I put in, I try and think about my competitors and what they would be doing and ask myself if they are working just as hard? I'm not saying it doesn't happen but it's a pretty rare thing for me to slack off."
Most swimmers who booked their Team GB slots at the Olympic trials in London earlier this year took a few days off to reset their focus on the Games, but Miley flew straight to a small swimming meeting on the continent to continue munching the miles.
While her team-mates were collecting their kit, an experience that is something of a rite of passage for every Olympian, Miley was competing at the Scottish Championships.
She didn't have anything to prove - she already has more medals than her parents know what to do with but she believes every competition represents a chance to improve.
Despite her 39-hour-a-week training schedule, Miley still describes herself as bubbly and smiley, which also happens to be her team nickname.
And her motto for success - 'if you do what you've always done, you'll get what you've always got.'
Four years ago in Beijing she was the baby of the team, turning 19 the day after the opening ceremony.
Former British coach Bill Sweetenham had long regarded her as a big-name for the future, even in her early teens he was describing her commitment as exceptional. Little was really expected but she still finished sixth in her first Olympic final.
Since then she has become a podium regular, winning the European and Commonwealth title in 2010 and silver at last year's World Championship.
Last time around she was happy to be part of the Olympic experience, now she feels like she belongs.
"I know that I can get in amongst the big names on an international stage," she adds. "I know I can manage and cope with all the pressure.
"Medalling at last year's worlds is a confidence booster but nothing is in the bag or guaranteed. In many ways those that didn't do so well will have worked even harder this year and be even hungrier. That means I need to work harder to."