In a recent radio interview British psychoanalyst Adam Phillips was discussing the importance of frustration: acknowledging it, accepting it, dealing with it as important determinants of a fulfilled self.
He might have been speaking of boredom in practicing music. Some of the most fulfilling aspects of my musicianship have emerged from my acknowledgement of utter boredom, with the Alberti bass, for example, which has become one of the features of Classical style that I most enjoy.