“I like the term “stretch” for describing what deliberate practice feels like, as it matches my own experience with the activity. When I’m learning a new mathematical technique—a classic case of deliberate practice—the uncomfortable sensation in my head is best approximated as a physical strain, as if my neurons are physically re-forming into new configurations. As any mathematician will admit, this stretching feels much different than applying a technique you’ve already mastered, which can be quite enjoyable. But this stretching, as any mathematician will also admit, is the precondition to getting better.”