Relentless self-improvement.

In other words, learn and train, and then test yourself in the real world, in a situation where it's possible to lose. Meaningful tests include getting the best score on a hard test, getting published in a prestigious journal, making a prototype that works, selling a lot of units, etc.

Most people don't bother to seriously improve themselves even after seeing other people succeed. Extraordinary motivation is required. One common source of this motivation is having a "tiger mother"; a narcissistic and status-seeking parent -- working obsessively is less painful than being cast out of one's family. Another common motivation is getting citizenship in a 1st-world country -- studying obsessively is less painful than living in a poor and politically-unstable nation. A few people just want success for its own sake, but most people can't summon the necessary will without an external threat.

Examples: Buzz Aldrin:

"The second man to walk on the moon?" his father said. "Number two?"

Arguably, Rational!Harry

Harry's mouth twisted bitterly...Always Harry had been encouraged to study whatever caught his attention, bought all the books that caught his fancy, sponsored in whatever maths or science competitions he entered. He was given anything reasonable that he wanted, except, maybe, the slightest shred of respect. (Ch.1)

Elon Musk recommends 1. rigorously evaluating plans to make sure they are realistic, and 2. working "like hell".

Richard Feynman enjoyed doing this to himself for the sake of solving interesting problems:

I used to do whatever I felt like doing - it didn't have to do with whether it was important for the development of nuclear physics, but whether it was interesting and amusing for me to play with.

This interest in solving difficult problems lets Feynman do well despite his relentless disregard for status:

You have no responsibility to live up to what other people think you ought to accomplish. I have no responsibility to be like they expect me to be. It's their mistake, not my failing.

Quirrelmort wonders about how to motivate people to munchkin their way to victory:

It is possible that you have already done everything you can. Yet I find this a very rare event indeed, and more often said than done. I suspect rather that you have only done what you customarily do. I cannot truly comprehend what drives others to break their bounds, since I never had them. People remain surprisingly passive when faced with the prospect of death. Fear of public ridicule or losing one's livelihood is more likely to drive men to extremes and the breaking of their customary habits. On the other side of the war, the Dark Lord had excellent results from the Cruciatus Curse, judiciously used on Marked servants who cannot escape punishment except by success, with no reasonable efforts accepted. Imagine their state of mind within yourself, and ask yourself whether you have truly done all that you can... (Ch. 92)

Relentless self-improvement is also the secret recipe for getting into prestigious universities, becoming powerful, and seeming to sparkle with extra life force. But, it's a high price to pay -- relentless self-improvement changes you and pulls you away from people who take the lazy path.