Life is made up of tests: the championship game, the final exam, the crucial presentation, the big recital. In those moments, we naturally tend to focus on the externals of our performance. Were we successful or not?

However, I think it might be more revealing to focus on the foundation: the days of preparation leading up to the performance. Specifically on this question: how do you know when you’re ready for a big test? How do you tell that you’re fully prepared?

While doing research for The Little Book of Talent I was fortunate enough to spend time at a Navy SEALs training base. The SEALs are rightly famous for their toughness, but I was more impressed with their brains — especially when it came to their methods for preparing for big tests. Case in point: last year’s mission to take out Osama Bin Laden, featured in the new book No Easy Day.

So how did the SEALs prepare for this test? They built a precise, full-scale mockup of Bin Laden’s compound in North Carolina, and they rehearsed. And rehearsed. And rehearsed. For several weeks, they ran endless variations of possible situations, from best-case scenarios on down to total disaster. The story is told in No Easy Day, the new book by fellow Alaskan Mark Bissonnette.

“Every single contingency was practiced to the point where we were tired of it,” Bissonnette writes.

I love that line, not just because it resonates with what I observed with the SEALs, but also because it gives us some insight into what real preparation for big tests truly is. You do something over and over — every single contingency — until you are tired of it.

This is not normally how we think about preparation. In normal life, we think that practice ends when we get it right a couple times in a row. But in truth, that’s when practice truly begins. The goal is not to do it right once. The goal is to do it often enough, in realistic conditions and under pressure, so that you can’t do it wrong.

So how do you know when you’re there? Here are a few tells.

• 1) You can perform the action while paying attention to other, extraneous things. For instance, if it’s a speech or a song, you can perform it while retaining a bit of brain space for noticing things. Call it automaticity, call it autopilot — the point is that you’ve built a reflex.
• 2) You are genuinely, deeply tired of it. You know every molecule of the material so well that if you ran through it one more time you might explode. This relationship — call it a healthy exasperation — is a good sign that you’ve mastered it.
• 3) You can vividly and accurately pre-create the Big Moment in your imagination — the sights, the sounds, the smells, the sensations. You don’t get surprised or knocked off balance by the big test because in a profound way, you’ve already experienced it.

All of which adds up to a basic truth known to the SEALs and others whose job is built on mastery: the trick of succeeding in the biggest moments is to use practice to transform them into a series of small, controllable moments.