Millar, whose first coaching experience was in 2010, says his latest gig is also helping him to improve as a coach, learning how to be encouraging to those who need that kind of support and identifying an approach that will get the best out of a young athlete.
As an athlete Millar himself is no stranger to setting goals and achieving success, which he loves, but knowing he's helped towards moulding another athlete towards attaining theirs as well is something else, he says.
"It's similar but different. You feel pride both times but the pride you feel in someone else's is more emotional.
The difference, he says, is being proud of another person compared to others being proud of you for winning a race.
Coaching, he says is something he sees a lot of potential in, planning to continue for many years to come.
But Millar has plenty more in him as an athlete and is already working towards his next three goals - breaking the New Zealand National 100m record, qualify for the Olympics and to break 10 and 20 second barriers.
He's confident of all three and says he's well ahead of where he thought he should have been at this time.
Scott Bartlett from Omanu Beach Surf Life Saving Club was excited about what Millar could bring to the club.
He said speed was vital for surf lifesaving athletes and having Millar coach their young members as they prepared for national competitions would not only improve the budding athletes' chances during competition, but also help keep the city's beaches safer through summer patrols.
"We believe we're very lucky to have someone of his calibre."
In the past Bartlett said Omanu has lost people to other clubs offering sprint training for their members.
This is the first time the club has offered a sprint programme and Bartlett believes the extra support for athletes aged 10-plus will give them an added incentive to remain with the club throughout their surf life saving career.
He says speed is a vital skill to have in any sport and believes Millar will only have a positive impact in building a high calibre of athletes in the club.