Usually breathing occurs for about an hour through the right nostril. Then for two to four minutes through both the nostrils. Then again through the left nostril for an hour and later for two to four
minutes through both. Then again through the right nostril. This cycle goes on continuously. By practising anulom-vilom pranayam one gradually gets used to breathing through both nostrils.
Endurance of pain increases mental strength and detachment towards worldly life and therefore the mind turns to Spirituality. By experiencing unhappiness destined actions are completed. However the real motive behind practising Hathayoga is not limited to merely bringing about an increase in the tolerance of the mind but to activating the kundalini.