"Surely, a person can't just wish themselves better". One cannot only wish, but wishing is part of it.

I have read many biographies of successful people, I have studied the issues of "success" academically, and I have been interested in performance in general for a long time. I have also performed pretty well across physical and mental disciplines.

Pedagogy depends on the subject, we know in many fields what works and what doesn't, and anyone who has spent as I have a few decades on this earth cannot but curse, benevolently of course, the many incompetent teachers and coaches and teaching methods they have had to endure in their younger years: those teachers and coaches had no clue. Or they were teaching for the masses, that is, to get their salaries and call it a day or a year.

But I think it is more interesting to think about "sacrifices" along the road to greatness" and "suffering."
Let's take sports again and think about the incredible suffering (or not) that some people go through to achieve greatness. In many sports, it is not empirically true that the best suffer and sacrifice more than others, and I have provided a few examples for team sports. I could provide 1,000 more, but we get the point.
For example, Messi, who is 1,000 times the soccer player I am, or rather was, I can guarantee that he did not train much harder than I did. He was only 1,000 times better than me and 10 times luckier to have a chance to perform: a bad knee injury at age 14 or hormone injections that did not work as planned, and we would not have had a Messi.

I recently read a pdf published by current world record holder and 10k speed skating world champion Van der Poel (https://www.howtoskate.se/). In his writing, he documents his training in the years immediately leading up to the 2022 World Championships. It is an extraordinarily instructive read because we can read from an analytical sports champion about his training, his mindset, his way of looking at things without the unnecessary "cultural" expectations and bravado of others who need to relate to Navy Seals, Kobe Bryant, Jordan, a couple of coaches who have been dead for 50 years, hard-nosed NFL players with CTE, and the "hustle culture."

One can start reading from the epilogue.

Mind you: his training was about as grueling as it gets, the very definition of physical suffering. He writes, "The hardest thing about this program was being able to complete it with a smile on my face. When I found a way to enjoy it, I was unstoppable [...] To me the challenge was not about suffering, but finding a way to endure hardship with ease [...] Be courageous. Don't overtrain, but stick to the Limit."
Grueling work, yes, but with a smile on his face. Is that suffering? Or "just" grueling work?

Recommended performance material: "Speed Trap," written by the late Charlie Francis, Ben Johnson's coach and performance mind extraordinaire. Van der Poel's "How to Skate 10k" pdf. All you can find written by Julio Velasco, probably the best volleyball coach ever. "Finding you Zone" by Lardon. "With Winning in Mind" by Bassham.
If one reads Tim Grover's book "Relentless", "Winning", they get the impression that high performance is all about suffering, sacrifices, the dark side. It sells well to an audience favorably disposed to this kind of U.S.-centric nonsense, but it is simply, in theory and practice, wildly not true.

Given "talent," the road to improvement and performance often goes through more work, but it always goes through better work-more effective, focused, deliberate-than that done by the competition.