"Yoga is not possible for him who eats too much, nor for him who does not eat at all, nor for him who sleeps too much, nor for him who keeps always awake." (16-VI)

In this verse, the rules pertaining to the Yogi’s food, sleep etc., are mentioned. Too much eating or eating more than one’s capacity would impair one’s health, which would force one to give up the practice of Yoga. If one eats that much food which is within one’s capacity, it protects him. But if he eats more than he can digest, it will do harm to him. Therefore a Yogi should not eat more than he can digest. At the same time he should not take less food as it would not sustain him to continue his Yoga practises.

This verse can also taken to mean that Yoga is not for one who eats more food than prescribed for a Yogi in the Yoga texts. According to Yoga texts, half of the stomach is to be filled with food; quarter with water and the remaining quarter for the movement of air.

Similarly, there is no Yoga for him who sleeps too much nor for him who keeps awake too long. Therefore keeping ever awake and indulging in excessive sleep are both harmful.

"To him who is moderate in eating and recreation, in his efforts in works, and in sleep and wakefulness, Yoga becomes the destroyer of sorrow." (17-IV).

How can one attain perfection in Yoga? He who limits his activities including eating, moving, drinking, sleeping, keeping awake etc., to proper measure is a successful Yogi. There should be no unevenness of any kind anywhere. Diet and recreation should be properly regulated. Excessive talk and sleep should be avoided. Wakefulness should be practised in due limits. One should also be moderate in the efforts in his works. Leading a life regulated in this way helps promote a healthy body and a healthy mind. He who follows these instructions carefully and practises Yoga becomes perfect in Yoga which puts an end to all sorrow.

"When the well-controlled mind is established in the self only, without longing for the objects of desires, then is one called steadfast in Yoga. (18-VI).

The mind of an ordinary man is restless because it always runs after the worldly objects. The mind is easily attracted by the objects of the world. It has also a tendency to go out from one object to another without any break. As a result of this fickleness of mind, man loses much of his energy. He also gets caught up in lot of problems. Therefore he has to withdraw his mind from all the worldly objects and focus it on his own self. When the mind is thus firmly established in the self, he will experience unprecedented joy and will be steadfast in Yoga.

In other words, when a man has no more cravings for objects of desires he will be able to fix his mind in the self. When the mind is thus anchored in the self, he is said to be established in Yoga or steadfast in Yoga.

"As a light in the windless spot does not flicker - this is the simile for the Yogi of subdued mind, practising concentration on the self" (19-VI)

In this verse a simile of the mind of the Yogi who is established in Yoga is offered. Just as a lamp kept in a place free from wind does not flicker, but keeps on burning bright, even so, the Yogi’s mind which has been fully controlled remains steady as the Yogi practises the discipline of Yoga, that is concentration on the self. The idea is, when the mind is brought under control, it becomes one-pointed very much like the light kept in a windless spot as a result of the practise of Yoga.

But to bring the mind under control, one has to give up all objects of desire. When all the thoughts of enjoying the worldly objects are given up then the Yogi’s mind gets easily established in the Self. What would be the condition of his mind when he meditates on the self? It would be like the flame of a lamp placed in a windless spot which burns steadily without flickering. An impure mind is unsteady due to the winds of desire blowing constantly. It is like the light kept in an open place full of wind. Whereas the mind which has attained purity as a result of its desirelessness remains steady in the Self without any disturbances.