The athlete watches videos on technique, dissects his rivals and hones his body. He is ready for anything, but never fame, for it comes like an avalanche without warning. One moment he's a boy in a cap and goggles. Next minute - 50.39sec precisely - he's a star requiring a security detail.
A nation wants to shake his hand, say his name and embrace him. It is touching, humbling, affecting, extraordinary, and it can also, in the months down the road, be unsettling. Fame gives the athlete so much and yet it will steal from him, too: It is going to be hard for Joseph Schooling to ever be himself any more. He's not just a human; he's now a hero.
The Mint in Brazil manufactured 2,488 medals, of which 812 were gold, and now one belongs to Schooling of Singapore. Each medal is 500g - but in truth, its impact is hard to gauge.
Perhaps it is best to let a weightlifter educate us. As the Georgian over-105kg champion Lasha Talakhadze said: "I can assure you it is easier to lift a weight than carry the meaning of the medal."
The medal is only 85mm in diameter, yet it brings a fame as wide as the borders of a nation. The medal signals the end of one adventure and the beginning of another: Greatness has been achieved and yet now greatness must be worn. As Chad le Clos, three years Schooling's senior at 24 and a conqueror of Michael Phelps in 2012, told The Sunday Times, fame isn't an easy business.
"The small advice I can give," he said, "is that it's a lot harder than you think."
Everything changes for the celebrated athlete with an Olympic gold medal. He can walk into any over-booked restaurant and find a table and choose any sponsor he wishes. It is fun but it is permanent. He cannot ever return to being nobody.
"You can't prepare for the fame," said le Clos, who has one Olympic gold and three silvers. "In my country, I was a national hero and I'm pretty sure he (Joseph) is going to be a huge hero in his country. (My advice is) just be yourself and don't let people change you. Don't let the money or the success, or the girls... don't let that change you. Just stay true to yourself, to your family."
Everybody hangs onto the hero's every gesture and waits for his every word. They'll tape it, Facebook it, discuss it. People can be forgiving if he errs and yet flame him for the mildest comment.
As the legendary Alexander Popov, the Russian swimmer with four Olympic golds and five silvers from 1992 to 2000, told The Sunday Times: "Being an Olympic champion is a huge responsibility. What you say, what you do, how you behave, everything is counted."
Popov, an Omega ambassador like le Clos, hunches his massive, blue-suited frame in Rio and explains what occurs with the winning of a first Olympic gold: "First of all, your status changes. Your behaviour should be according to the new level that you have achieved in sport. Quick changes, for better or for worse I'm not sure, in life are not so easy to handle. Because of the pressure, you lose focus and everything. He (Joseph) has to concentrate on his swimming."
Nations wear gold differently and so do athletes. In China, with so many champions, one gold creates a ripple; in Singapore, waiting for its first gold, it generates a marvellous wave.
Champions, too, digest victory differently: Some fancy fame, swim with it, wear it easily; but many find gold a difficult weight and are initially overcome by victory. At 21, a life's purpose has been achieved. Now what?
For le Clos, it was a struggle initially: "After the Olympics you kind of lose that hunger to train, you have that post-Olympics depression as they call it. I'm sure he (Joseph) will feel that."
Then the South African smiles and adds: "But he must keep pushing through because I want him to be in good form next year when I race him again."
From the day he won the 100m butterfly, a label has been affixed to Schooling's name: reigning Olympic champion. Every story he appears in, every function he shows up at, it will be mentioned. It makes him the one to chase for an autograph and also to hunt down in the pool. Beating him will be the pre-training vow of every butterflier on the planet.
Schooling will probably enjoy this, being at the pinnacle, being challenged, and he knows that champions don't sun themselves forever in the spotlight; they sweat.
As Popov says, the focus has to be on training and swimming "because from now on, (Schooling) cannot swim poorly. You have to produce quality now instead of quantity. Quality in training, in competition, in results. You have to be steady, reliable, and you have to be a benchmark for everyone else".
This is the pressure, to perform, to go faster, to win, to repeat.
"There's always pressure," said le Clos. "I don't worry too much about what people think about how I swim and how I'm swimming. I have a lot of critics, I have a lot of haters but I feel like there's so many people out there who support me. If you swim for something greater than yourself, it can help you achieve great things."
The smart athlete finds a balance; he shakes the public's hands, manages the media, does appearances and trains. He surrounds himself with a team, which will assist him not indulge him, which will be there for him in hard times and yet tell him tough truths at all times.
Schooling is lucky for he has fine people in his corner: his parents, his mentor Sergio Lopez, his coach Eddie Reese - all of them proud, protective and plain-speaking.
But Schooling's finest ally right now is his own, unspoilt self. He has an easy smile and a modest manner and a desperation to go faster - now he wants the world record - that will sustain him.
If he has been fashioned quickly by us into a role model, he should find some for himself. From tennis' Roger Federer to golf's Tseng Ya-ni, there are fine champions out there whose behaviour and perspective are worth imitation: For all the pressures they face, they never forget that, in a planet so full of suffering, they are the fortunate ones.
Yet Schooling is also going to need help, from his people and his nation. Singapore has been delighted by him and is now devoted to him, and a nation's affection is a glorious thing. And yet, as the years roll on, the greatest gift a nation can give him is to let him be himself.
To not imprison him with worship as other countries do to their athletes, wherein they cannot even walk their city streets. To allow him his privacy, to not judge him too harshly, to let him make mistakes, and to enjoy what he has done instead of only waiting for what he might do next. He's our hero but he's also only human.
Schooling has returned to America and also to the place where he was made, where he will chase the future and where he will always find escape: The swimming pool. Half-submerged in liquid, with only the black line at the bottom for company, life will begin again for him. No cameras, no talking, no smiling. All he will hear in the silent waters is the familiar sound of his own ambition.