I believe the concept of finding aspects of ‘flow’ within your life is fundamental to personal happiness. Csíkszentmihályi book on Flow describes it as completely focused motivation: a single-minded immersion. Harnessing the whole self in the service of performing and learning, a spontaneous feeling of joy or rapture. There are clear parallels with the Ashtanga Yoga method and those moments of flow within the physical practice of yoga.
Csíkszentmihályi’s flow model, with its axis of ‘challenge’ and ‘skill’ place ‘flow’ in the upper-right quadrant, with high challenge and high skill. ‘Flow’ is bordered on one side by ‘control’ where we are not quite challenged enough, and on the other side by ‘arousal’ where the mind is heavily engaged and perhaps we are still learning unfamiliar skills.
Balance, between the mental states of ‘arousal’ and ‘control’, to find that ‘flow’ within a physical yoga practice.