The problem to which Peaty refers was his quest for a third consecutive Olympic 100m breaststroke gold last July.
He had to settle for silver by an agonising 0.02 seconds, having contracted Covid-19 earlier in the week.
He was in tears afterwards and again soon after when holding his three-year-old son, George.
“I got ill on the day you are most healthy,” says Peaty, who also won relay gold in Tokyo in 2021.
“I have got to laugh about it because it is one of those incredibly painful moments but I don’t see it is one of those things I am always going to look back on and say ‘what a horrible moment’.
“It has taught me so much about myself, about my future and where I want to apply that experience to my potential next Olympic Games.
“It is just life. It will be tough sometimes and will be easy sometimes too.”
Peaty’s first two Olympic golds – in Rio de Janeiro and then Tokyo – came during his period of dominance.
The third individual medal, not quite the colour he wanted, followed his time out of the sport after issues with alcohol and his mental health.
Since then Peaty’s long-time coach Mel Marshall has left for a job in Australia, leading plenty to believe he would walk away from the sport, but the Englishman committed to another Olympic cycle last week after the 50m breaststroke races were added to the schedule for the Los Angeles Games in 2028.
“I watched the press conference and thought ‘this is going to change the sport for everyone’,” Peaty says.
“Swimming is one of those sports where it is incredibly demanding.
“You are doing 4,000 to 5,000m in the morning, doing a whole day of work or school then 4,000m at night.
“Sprinting is a little bit different because you don’t have to commit to the metres as much.
“You still have to put the time in, it is going to be difficult like anything, but it is going to give longevity to those athletes that have been doing that for a long time, are getting tired of the sport and can train a bit differently.”
The Aquatics GB Swimming Championships began on Tuesday – and are live on BBC iPlayer until 20 April – but Peaty will not defend his title.
He is making a careful return to the sport after a break post-Paris with LA the ultimate goal, by which time his son will be eight.
“He is going to fully appreciate what it is like to be at an Olympic Games,” Peaty says. “That is the journey we are on.
“It is no longer a selfless decision it is a family and broader decision.
“I race fastest when I am happiest. You have got to get results, most of the time you will not be happy but at least there is a balance there.
“That is something I learned from my previous cycle into Paris.”
