"10,000 hours of training, according to Malcolm Gladwell’s book Outliers. Gladwell based this assertion on the work of Anders Ericsson, who studied classical violinists and found that, in every case, it had taken a regimen of 2-3 hours a day for 10 years to develop their abilities. Later research by Ericsson and others confirmed similar results in other fields."
http://www.lifehack.org/articles/lifestyle/on-luck-success-a...