In principle any skill or discipline one can master on one’s own will serve: meditation and prayer if one is so inclined; exercise, aerobics, martial arts for those who prefer concentrating on physical skills. Any specialization or expertise that one finds enjoyable and where one can improve one’s knowledge over time. The important thing, however, is the attitude toward these disciplines. If one prays in order to be holy, or exercises to develop strong pectoral muscles, or learns to be knowledgeable, then a great deal of the benefit is lost. The important thing is to enjoy the activity for its own sake, and to know that what matters is not the result, but the control one is acquiring over one’s attention.
―Mihaly Csikszentmihalyi, Finding Flow: The Psychology of Engagement with Everyday Life