Media playback is not supported on this device
There has never been a need or desire to brag about her talents. Her swimming speaks for itself.
But the 17-year-old, who has cerebral palsy, has recently taken to sporting a snazzy bright hat to make sure she is noticed. It is not a fashion statement or shameless attempt at attention-seeking, simply a safety precaution.
"Last year, she had her first epileptic seizure," mum Sharon told BBC Sport. "These are quite a normal thing with cerebral palsy unfortunately.
"We didn't want to stop her swimming, so we bought her an orange hat, so when she does her training sessions she is easy to pick out in the lanes just in case something happens in the water."
The first seizure was "horrifying". Various tests and plenty of worrying and uncertainty followed. As have "at least six" big seizures in the past 12 months.
"It doesn't faze her," Sharon added. "They have all been in the night so she is not really aware of what has happened.
"She just happily takes her medication and gets on with it. And the lifeguards are all aware that she is the one in the special orange hat."
Milne had a stroke when she was born and is missing a third of her brain on the left side, something she previously joked "sounded cool". It means she has restricted movements on her right side.
But the epilepsy - the latest obstacle - has not affected Milne's progress, times or enthusiasm.
Having taken her GCSEs and spent a year at college, she now combines her swimming with an apprenticeship, working as a lifeguard and swimming assistant at the Meres Leisure Centre in Grantham, not far from her Lincolnshire home.
She is still training five or six times per week at Grantham Swimming Club, and she is ranked in the top two in the country in her category at six events in long and short course this year. And she is now in the highest of two levels for Para-swimmers in the country - the England Programmes Development.
Her progress from the Spotlight Programme has given her plenty to think about, but she is embracing the challenge.
"Times are obviously important because now she is more senior," explained her liaison coach Carl Cooper. "But it's now about taking information on board and the processes - not just the swimming.
"How do we make progress so she is world class? We get the athlete looking at their training and what they do leading up to it. We set goals and work on skills."
Cooper is in regular contact, and sees Hayley about 10 times per year. She has one or two National Camps and one or two Zonal camps each year, as well as more bespoke training, and plenty of form-filling to keep tabs of her progress.
Milne has taken to the step up. She desperately wants to make the next Paralympics and is well aware of the dedication needed to make that happen.
She said: "It's harder for me swimming with swimmers who aren't disabled but it's good. I want to go to Tokyo 2020.
"Two of my friends have been to the Paralympics. I chatted to them during the Paralympics and it made me want to go even more."
Ellie Robinson won Paralympic gold in the S6 50m butterfly at Rio 2016, as well as earning bronze in the S6 100m freestyle, while Rebecca Redfern won silver in the SB13 100m breaststroke.
Cooper said Milne has the potential and talent to join her friends at the next Games.
"She is doing really, really well," Cooper added. "Investment is no guarantee. but we are making sure she is doing the right things and is getting the best environment to progress - and she seems to be."
Swimmers are regularly assessed to make sure they still deserve to be on the programmes, and with Milne it was an "easy decision", even though Cooper says there is plenty of new talent pushing her hard.
Her hopes of competing in Japan are greatly helped by an exemplary attitude.
"Hayley is such a smiley, happy swimmer and that makes things easier," Cooper explained. "But she is also very focused.
"She comes across as very driven and always wants feedback. She wants to know what she is doing is right and how she can improve. It's about little margins and she understands that."
Sharon added: "It is remarkable where we have come from. She is a joy. She never lets you down.
"She has never laboured on the fact that she can't do things. She just soldiers on, does her best and people appreciate that.
"We are so proud of her. It is my life as well as her's. We live, eat, breathe and sleep swimming. It's brilliant.
"It would be fantastic if she made Tokyo."
As one of the best young Para-swimmers in the country, Hayley Milne stands out.