The sixth chapter of the Bhagavad Gita is Dhyana Yoga. In this chapter, Krishna reveals the Yoga of Meditation and how to practise this Yoga. He discusses the role of action in preparing for Meditation, how performing duties in devotion purifies one's mind and heightens one's spiritual consciousness. He explains in detail the obstacles that one faces when trying to control their mind and the exact methods by which one can conquer their mind. He reveals how one can focus their mind on Paramatma and unite with the God.
That yogi who, being established in unity, adores Me as existing in all things, he exists in Me-in whatever condition he may be.OPEN VERSE
O Arjuna, that yogi is considered the best who judges what is happiness and sorrow in all beings by the same standard as he would apply to himself.OPEN VERSE
Arjuna said: O Madhusudana (Krsna), this Yoga that has been spoken of by You as sameness, I do not see its steady continuance, owing to the restlessness (of the mind).OPEN VERSE
For, O Krsna, the mind is unsteady, turbulent, strong and obstinate. I consider its control to be as greatly difficult as of the wind.OPEN VERSE
The Blessed Lord said: O mighty-armed one, undoubtedly the mind is intractable and restless. But, O son of Kunti, it is brought under control through practice and detachment.OPEN VERSE
My conviction is that Yoga is difficult to be attained by one of uncontrolled mind. But it is possible to be attained through the (above) means by one who strives and has a controlled mind.OPEN VERSE