Mind by its very nature is unsteady and restless; it always wanders away from the point of concentration. The true seeker on the path of meditation will therefore get despaired at his inability to fix his mind on a focal point, contemplating on the Self. During the practice of meditation although the sense organs are controlled, the chasing of the sense objects by the mind will continue and cause dejection in the seeker.
The reasons for this roving mind may be many such as memories of the past, proximity of the tempting sense objects, attachments etc. Sri Krishna directs that whatever be the reason for the restlessness of the mind, the seeker is not to lose hope. On the contrary he should understand that these tendencies are the very characteristics of the mind and the process of meditation is the technique to eliminate them.

The means of bringing under control the restless mind are the realization of the illusoriness of sense-objects and the cultivation of indifference to them. Through practice of discrimination and detachment the mind gradually attains inner peace.

The Lord advises the seeker to bring back the mind that has gone out on a roaming mission. As soon as the mind is withdrawn through will power it will go out again because mind means flow of thoughts and it can never be steady without any motion. Therefore in the meditation when the mind is withdrawn from the sense objects it should be provided with an alternative to keep it busy. That alternative is its application towards contemplating on the Self alone.
RESULT OF THE YOGA OF MEDITATION

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In the beginning, the yogi who is thus engaged in making the mind established in the Self, etat vasamnayet, should bring this (mind) under the subjugation; atmani eva, of the Self Itself; niyamya, by restraining; etat. it; tatah tatah, from all those causes whatever, viz sound etc.; yatah yatah, due to which, doe to whatever objects like sound etc.; the cancalam, restless, very restless; and therefore asthiram, unsteady; manah, mind; niscarati, wanders away, goes out due to its inherent defects. (It should be restrained) by ascertaining through discrimination those causes to be mere appearances, and with an attitude of detachment. Thus, through the power of practice of Yoga, the mind of the yogi merges in the Self Itself.