In the 1990's, psychologist K. Anders Ericsson conducted an experiment with the Berlin Academy of Music. He divided the school's violinists into three groups: the elite, the good, and those that were unlikely to ever play professionally.
All of the kids had started playing when they were 5 years old, but what divided them, aside from ability, was simply how many hours each had spent practicing. The really good ones had totaled 10,000 hours of practice, while the good ones had only managed to squeak away on the catgut for 8,000 hours or so.
The underachievers? Just 4,000 hours of practice.
The most surprising thing was that they really couldn't find any "naturals." Nor could they find any grinders, people who just worked harder than everybody else but just didn't have the talent to become elite.
The thing that distinguished one from another was simply hard work, nothing else.
But the weird thing is that 10,000 hours — roughly the amount of practice a truly committed devotee could accrue over 10 year — keeps popping up in different fields. Whether you're a writer, a concert pianist, a basketball player, computer programmer, or chess master, true greatness seems to pivot on that magic number.