He may practise meditation until Doomsday, mutter the hundred and eight different mystic spells, sit in all the sixty-four postures of the yoga of body control, hold his breath for a whole hour or vary its rhythms in every conceivable manner, but the Overself will remain stubbornly remote unless he frankly faces and successfully fights out his struggle against his own ego in his own heart. No physical contortion, exercise, or manipulation can ever take its place. Such yoga exercises can discipline his body, give him control over it, but they cannot provide a passport into the higher region. This and this alone is the only yoga that really counts in the end on this strange quest, because demanding all it gives all.
-- Notebooks Category 5: The Body > Chapter 5: Exercise > # 138