Meditation Follows Concentration - Part 7

If there is much strain in your meditation, reduce the duration of each sitting for a few days.
Do light meditation only. When you have regained the normal tone, again increase the period. Use your common-sense throughout your Sadhana. I always reiterate on this point. 70 MEDITATION “Though men should perform Tapas standing on one leg for a period of 1,000 years, it will not in the least, be equal to one-sixteenth part of Dhyana-Yoga (meditation).” Pingala-Upanishad. Those who meditate for four or five hours at a stretch can have two meditative poses. Sometimes the blood accumulates in one part of the legs or thighs and so gives a little trouble. After two hours change the pose. Or stretch the legs at full length and lean against a wall or pillow. Keep the spine erect. This is the most comfortable Asana. Or join two chairs. Sit in one chair and stretch the legs on another chair. This is another contrivance.
You must daily increase your Vairagya, meditation and Sattvic virtues such as patience,
perseverance, mercy, love, forgiveness, etc. Vairagya and good qualities help meditation.
Meditation increases the Sattvic qualities.
Considerable changes take place in the mind, brain and the nervous system by the practice
of meditation. New nerve-currents, new vibrations, new avenues, new grooves, new cells, new
channels are formed. The whole mind and the nervous system are remodelled. You will have a new heart, a new mind, new sensations, new feelings, new mode of thinking and acting and a new view of the universe (as God in manifestation).
From - SRI SWAMI SIVANANDA

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