I discovered when I went all out, when I put 100 percent of my energy into some intense, impossible task - when my heart was jack-hammering, when lactic acid was sizzling through my muscles - that's when I felt good, normal, balanced.

The sweet spot: that productive, uncomfortable terrain located just beyond our current abilities, where our reach exceeds our grasp. Deep practice is not simply about struggling it's about seeking a particular struggle, which involves a cycle of distinct actions.

Baby steps are the royal road to skill.

Practice makes myelin, and myelin makes perfect.

Although talent feels and looks predestined, in fact we have a good deal of control over what skills we develop, and we have more potential than we might ever presume to guess.

There is no substitute for attentive repetition.

To sum up: it's time to rewrite the maxim that practice makes perfect. The truth is, practice makes myelin, and myelin makes perfect.

Skill is a cellular insulation that wraps neural circuits and that grows in response to certain signals.