In the book Flow: The Psychology of Optimal Experience, author Mihaly Csikszentmihalyi highlights the importance of finding the right balance.
He uses the term "flow" to describe the mental state where a person is fully immersed in an activity, performing at his or her best, and feeling energized throughout the process. One of the keys to achieving this state is finding the perfect balance between challenge and skill on one axis and anxiety versus boredom on the other.
Via Sandeep Gautam