He had been living out of home for two years so he could play for the Bendigo Pioneers in the TAC Cup, and suddenly found himself in Melbourne under bright lights and in full view of television cameras.
Watch Tarrant's highlights from the early years of his career.
It was a huge adjustment for the boy from Mildura, one that took him many years to adapt to.
"It was quite a young age and I had to grow up fast, and I grew up at probably the biggest football club in Australia with cameras in my face," Tarrant said this week, after announcing he will retire at season's end.
"It's changed a lot; they help young players a lot through those early stages now but I found it quite difficult at the start and it took a while to adjust to that professionalism."
Tarrant's career in photos.
In fact, it took a club change and relocation to the other side of the country for the penny to drop for Tarrant.
After a period in 2000 during which he considered quitting and returning home, and a late night incident with teammate Ben Johnson at a venue in Port Melbourne in 2006, he was traded to Fremantle at the end of the season.
He spent four years in Perth, where without the 'influences' in Melbourne and with a quiet life alongside wife Lauren, he started to think about how he wanted the second half of his AFL career to play out.
"You do start to realise you have to look at yourself in the mirror and think, 'I really want to end my career well and being respected as well', which is a big thing," he said.
"I did say to the boys I was very talented but I don't think I was respected earlier in my career."
Watch Tarrant in the famous Sunsilk ad from 2003.
Coach Nathan Buckley, who played alongside Tarrant between 1998 and 2006, admitted he was pleasantly surprised at the person Tarrant had become when he returned to the Magpies for the 2011 season.
"It only highlights how strong that development has been and how much maturity that he has shown in recent years to become the man he is," Buckley said.
"I reckon there was plenty 'Taz' loved about the game but there wasn't a lot outside of actually playing it he wanted to be a part of.
"I think football as a culture cops a bit of a whacking from time to time, but 'Taz' has been able to mature within the football culture at Collingwood and Fremantle.
"The individual needs to decide to do it and 'Taz' has decided to do it and he's come out of his football experience with some real positive experiences and he's set himself up for whatever his future is because of it."
Tarrant's life after football will initially involve travel and time spent with Lauren.
See Tarrant speak on The Club on Tuesday night.
He has business interests he says will keep him busy, and he'll spend some time away from the game for the first part.
Right now, he's reflecting on his favourite moments in his career - that mark on the Queen's Birthday at the MCG in 2001, kicking the winning goal after the final siren against Adelaide in round seven, 2003, and the preliminary final victories against Adelaide (2002) and Port Adelaide (2003).
Tarrant says they'll be with him forever, just like the fact he's retired on his own terms.
"If you're still making the same mistakes that you made in your teens and your early 20s when you're 30, you must be a fool," Tarrant says.
"I feel like I've matured over time.
"When I came back to the club, I said I want to do everything right on and off the field and I think the guys know what they get when I'm on the field - I give it all I can and I try to beat my man whenever I can.
"Off the field, I've found that I've really worked hard on that as well and I've been a good influence around the club, which I'm really happy about."
Jennifer Witham is a reporter for AFL Media. Follow her on Twitter @AFL_JenWitham.
