Then he flagellates himself publicly, questions whether he has what it takes.
And the next time he is on verge of achieving something, he remembers the last collapse, and the previous one, and the one before, and under the burden of expectation and memory he blows up again.
So much of sport is played in the mind, and after his fourth-round Wimbledon exit to Flavio Cobolli de Minaur's mind is again in a dark place.
"It's a tough one. Overall, just not what I expected of myself," the 27-year-old said after the straight-sets loss.
"I think one of us went out to win the match, and the other went out not to lose the match. It's pretty self-explanatory who was who.
"It breaks me inside. That's the reality of it. Many, many hours gets put into my craft, and countless years to have moments like these. To not step up to the plate, it's truly gut-wrenching.
"How do you explain it? Just not good enough mentally. That's how you explain it.
"The issue is playing this match like I've got the weight of the world on my shoulders. I need to deal with it better, because if not, I'm just not going to be able to achieve the goals and dreams I've got.
"Sadly, it just feels like (these results) keep on coming. This is just another one to add to the tally."
The missed opportunities, the Sydneysider added, accumulate. "And the goals, the beliefs, the dreams that you have, they start fading away or they feel a little bit further away than when they once were.
"You go through moments in your career, times where you feel that there's opportunities to be taken, to take the next step, to make it to the next level. And to fall short constantly, you start doubting whether you're going to be able to take it to the next step.
"It's a battle that I deal with every day."
De MInaur, who has yet to progress beyond the last eight at a major, added: "I think the tennis is there to win these types of matches, if I can just play tennis and not worry about anything else.
"I wasn't able to do that, and that's why I'm in this position right now. I either improve or we'll see the same results again and again.
But, added the world No.6, he wasn't a quitter.
"I'm a competitor through and through. So I'll get back up, and I'll give myself another chance.
"I just want it to happen to keep giving me that hope. If not, this is a tough, tough sport to play with with no hope."
For now, he has the perfect distraction, his imminent marriage to British player Katie Boulter.
"I've got some pretty big things happening soon, stuff that I'm very excited for. My best way forward is to channel my focus into that, into something positive, and that should help put this in the past and get on with what's next."
