While all these practices are very advantageous, and perhaps necessary, they should not be resorted to all at once, in an extreme measure. Moderation is a greater virtue than complete abstention. Complete abstention may not be so difficult as moderation. Moderation is more difficult. For instance, to speak in a moderate and acceptable manner poses a greater difficulty for a person than to observe complete Mauna or silence.
Yoga is, a moderation of conduct and an internal adjustment.
It is not an extreme step that one takes, though sometimes an individual seeker goes to extremes unavoidably due to his very nature. That is why we run to monasteries and sequestered places. No human individual can escape this eventuality of being stirred inside in a holy manner, which may look like something extreme to the poor body which is not used to these conditions of thinking and feeling. The first one that he mentions is 'illness', physical illness. One has to guard oneself against this possibility.