A recent father and full-time consultant, training is now something the 29-year-old does when life allows, rather than the other way around.
He still hits the pool a few times a week but it's Melbourne's bike lanes, not swimming lanes, where he's putting in the real work.
A decade on from his gold-medal win in the 400-metre freestyle at the 2016 Rio Olympic Games, Horton is gearing up to cycle across Tasmania to raise money for cancer research.
He will be one of nearly 200 people taking part in Tour de Cure's Signature Tour, a nine-day cycling event from Canberra to Tasmania from March 12.
Horton will tag along for two days of the event, which will take him across the Apple Isle.
"It's the closest you can get to what it feels like being on the Olympic team without actually being on the team," he told AAP, reflecting on his time during 2025's Signature Tour in far north Queensland.
Riders spend hours side by side in a peloton, rotating through the front of the group as fatigue sets over five- or six-hour days.
"It's physically, it's hard, but emotionally, probably harder," he said.
"You're always having very meaningful, deep conversations."
Stories are shared on the road and again over dinner at night. Many have been through treatment or lost loved ones to cancer.
"For me, I haven't had anyone personally close to me affected by cancer yet," he said.
"Statistically, it's probably going to happen at some point."
Over 20 years, Tour de Cure has raised more than $158 million and funded more than 1220 cancer projects.
The event is not a race in the traditional sense but Horton admits there might be the odd hill where instincts kick in.
"The goal for this year is to raise $2 million but my other goal is to beat Richie Porte up a hill," he said, in a nod to the Launceston cycling legend who will also be making his return to the tour.
Cycling has always a part of Horton's training regimen but largely taking place indoors, often inside a heat chamber.
"If I enjoyed that, imagine how much I'm going to enjoy being out in the world," he said.
As for lessons learned from 2025's tour, the Olympian has one practical tip.
"It's called butt cream," he said.
Tour de Cure marks its 20th anniversary in 2026 and has raised nearly $1.3 million towards a goal of $2 million.
It has contributed to more than 230 world-class scientific breakthroughs and delivered thousands of nights of accommodation for rural families affected by cancer.
"It's getting bigger and bigger every year," Horton said.
"It's a fantastic thing to get around when you know that cancer can touch us all at some point."
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