What separates experts from the rest of us is that they tend to engage in a very directed, highly focused routine, which Ericcson has labeled "deliberate practice." Having studied the best of the best in many different fields, he has found that top achievers tend to follow the same general pattern of development. They develop strategies for consciously keeping out of the autonomous stage while they practice by doing three things: focusing on their technique, staying goal-oriented, and getting constant and immediate feedback on their performance. In other words, they force themselves to stay in the "cognitive phase."
Amateur musicians, for example, are more likely to spend their practice time playing music, whereas pros are more likely to work through tedious exercises or focus on specific, difficult parts of pieces. The best ice skaters spend more of their practice time trying jumps that they land less often, while lesser skaters work more on jumps they've already mastered. Deliberate practice, by its nature, must be hard.
Moonwalking with Einstein: The Art and Science of Remembering Everything
by Joshua Foer
The Role of Deliberate Practice in the Acquisition of Expert Performance (pdf file)
K. Anders Ericsson
Psychological Review 1993, Vol. 100, No. 3. 363-406