"I'm an open book," he admits. "And that's the way I like to be, because, ultimately, if I'm honest with myself, then I can't hide from the issues that I need to improve on."
It's good to see Australia's great tennis trier smiling again as he reflects in an interview with AAP on how there were times during 2025 when that 'open book' must have been a horror read for all his supporters.
For we really did worry about the Demon's demons.
Like that day in May when, blank-eyed, he poured his heart out after capitulating from two sets up against Alexander Bublik at Roland Garros, lamenting how he was burned out, disenchanted and needed to walk away from tennis.
Or like that crushing loss at the ATP Finals in Turin to Lorenzo Musetti, a defeat somehow conjured from the clutches of victory which convinced him to wail publicly that he was being "eaten alive" and "mentally killed" by all these disappointments.
So on a dank morning in London at an end-of-year Ultimate Tennis Showdown event, what a relief to find Australia's premier player so upbeat and positive again about his 2025 travails and even more enthused by his prospects for 2026.
Had this perfectionist at last eased up on being so hard on himself?
"Yeah, it's a work in progress, right?" he grinned. "Ultimately, I wish I could say I've fixed that, but it's a double-edged sword.
"Because the reason I've been able to continuously improve is that I'm so critical and hard on myself, but at the same time, sometimes I need to take a step back, realise what I have achieved, and give myself a pat on the back.
"I need to realise that, as I'm sitting here right now, I'm No.7 in the world, my highest end-of-year ranking. I've had my best year ever, most match wins, another title (in Washington) and was potentially two points away from finishing the year in the top five.
"So I'll just continue to work on my goals, strive to keep improving - but at the same time, be nicer to myself!
"(Golfer) Scottie Scheffler expressed exactly that in a recent brilliant interview, that you work your whole career to achieve a certain goal, and you feel content and happy for a couple moments - and then you're on to the next thing; there's always more."
So when de Minaur offers his verdict on 2025, he thinks it's time to smell the roses.
"I do think I've improved, and my game has improved, as it's kept doing over the years, and I'm proud of that," he says.
"There's still aspects technically where I can get better, and we'll keep working on that, but what's going to help me make the biggest step is my mental approach. It's going to be a mindset shift.
"And that means not worrying about results as much as the way I want to play. In the big matches, I didn't play the way I wanted because I was too focused on the result, and not, I guess, on the process.
"Ultimately, that's a big shift in mindset that needs to happen for me to take the next step."
And he feels it's already begun. Two days after that cruel loss to Musetti, de Minaur's first ever win at the season-ending championships, over Taylor Fritz, felt huge.
"Not a life-changer," he shrugs - but still perhaps the most significant victory yet in his still burgeoning career.
"It was a bit of an 'A-ha!' moment of how it's amazing what can happen when you're going to stick to your guns, stick to playing a certain way and, yeah, it doesn't matter what the result is. I was very proud of that win."
Next year is going to be life-changing for him.
Certainly off the court as he and his British tennis star fiancee Katie Boulter tie the knot - and he, for one, won't hide he'll be relieved when the endless wedding planning is out the way.
But on court? The planning, the plotting never stops. Here's a man still seeking to finally break through that glass ceiling of grand slam quarter-finals at the seventh attempt, and he reckons he'd "love nothing more" than that happy event occurring at Melbourne Park in January.
For he's still convinced "I've not reached my peak yet". He's only 26, quick as lightning, fit as a butcher's dog and as one TV commentator once noted, memorably if somewhat unflatteringly, as indestructible of spirit as a scurrying cockroach.
When he looks back on those public outpourings of misery at Roland Garros and Turin, he reflects unapologetically: "I just wanted to kind of speak from the heart. A lot of the time, we try to put on a brave face, try to act or say that nothing fazes us.
"But as tennis players, there is a lot that fazes us, right? So it's about how you handle it, how you overcome it, how you move past these things. That's what defines you."
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