Ericsson's research suggests a third cliché as well: when it comes to choosing a life path, you should do what you love — because if you don't love it, you are unlikely to work hard enough to get very good. Most people naturally don't like to do things they aren't "good" at. So they often give up, telling themselves they simply don't possess the talent for math or skiing or the violin. But what they really lack is the desire to be good and to undertake the deliberate practice that would make them better.

"I think the most general claim here," Ericsson says of his work, "is that a lot of people believe there are some inherent limits they were born with. But there is surprisingly little hard evidence that anyone could attain any kind of exceptional performance without spending a lot of time perfecting it." This is not to say that all people have equal potential. Michael Jordan, even if he hadn't spent countless hours in the gym, would still have been a better basketball player than most of us. But without those hours in the gym, he would never have become the player he was.

Ericsson's conclusions, if accurate, would seem to have broad applications. Students should be taught to follow their interests earlier in their schooling, the better to build up their skills and acquire meaningful feedback. Senior citizens should be encouraged to acquire new skills, especially those thought to require "talents" they previously believed they didn't possess.

And it would probably pay to rethink a great deal of medical training. Ericsson has noted that most doctors actually perform worse the longer they are out of medical school. Surgeons, however, are an exception. That's because they are constantly exposed to two key elements of deliberate practice: immediate feedback and specific goal-setting.

The same is not true for, say, a mammographer. When a doctor reads a mammogram, she doesn't know for certain if there is breast cancer or not. She will be able to know only weeks later, from a biopsy, or years later, when no cancer develops. Without meaningful feedback, a doctor's ability actually deteriorates over time. Ericsson suggests a new mode of training. "Imagine a situation where a doctor could diagnose mammograms from old cases and immediately get feedback of the correct diagnosis for each case," he says. "Working in such a learning environment, a doctor might see more different cancers in one day than in a couple of years of normal practice."

If nothing else, the insights of Ericsson and his Expert Performance compatriots can explain the riddle of why so many elite soccer players are born early in the year.

Since youth sports are organized by age bracket, teams inevitably have a cutoff birth date. In the European youth soccer leagues, the cutoff date is Dec. 31. So when a coach is assessing two players in the same age bracket, one who happened to have been born in January and the other in December, the player born in January is likely to be bigger, stronger, more mature. Guess which player the coach is more likely to pick? He may be mistaking maturity for ability, but he is making his selection nonetheless. And once chosen, those January-born players are the ones who, year after year, receive the training, the deliberate practice and the feedback — to say nothing of the accompanying self-esteem — that will turn them into elites.

This may be bad news if you are a rabid soccer mom or dad whose child was born in the wrong month. But keep practicing: a child conceived on this Sunday in early May would probably be born by next February, giving you a considerably better chance of watching the 2030 World Cup from the family section.