Sarah Lewis, in The Rise: Creativity, The Gift of Failure, and The Search For Mastery, she discusses the mindset of archers at target practice. Her definition of mastery may be useful for educators.
Mastery requires endurance. Mastery, a word we don’t use often, is not the equivalent of what we might consider its cognate–perfectionism–an inhuman aim motivated by a concern with how others view us. Mastery is also not the same as success–an event-based victory based on a peak point, a punctuated moment in time. Mastery is not merely a commitment to a goal, but to a curved line, constant pursuit (p. 7-8).
See also Otherwise Ignored Ideas and (other posts about failure here)