Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura has commented as follows upon this verse: "One who has not yet developed interest in Kṛṣṇa consciousness should give up all material motives and train his mind by following the progressive regulative principles, namely chanting and remembering Kṛṣṇa and His name, form, quality, pastimes and so forth. In this way, after developing a taste for such things, one should try to live in Vṛndāvana and pass his time constantly remembering Kṛṣṇa's name, fame, pastimes and qualities under the direction and protection of an expert devotee. This is the sum and substance of all instruction regarding the cultivation of devotional service.
(Nectar of Instruction).

By practice of yoga one becomes gradually detached from material concepts. This is the primary characteristic of the yoga principle. And after this, one becomes situated in trance, or samādhi, which means that the yogī realizes the Supersoul through transcendental mind and intelligence, without any of the misgivings of identifying the self with the Superself. Yoga practice is more or less based on the principles of the Patañjali system. Some unauthorized commentators try to identify the individual soul with the Supersoul, and the monists think this to be liberation, but they do not understand the real purpose of the Patañjali system of yoga. There is an acceptance of transcendental pleasure in the Patañjali system, but the monists do not accept this transcendental pleasure, out of fear of jeopardizing the theory of oneness. The duality of knowledge and knower is not accepted by the nondualist, but in this verse transcendental pleasure—realized through transcendental senses—is accepted.
(Bhagavad-Gita---6:20-23--purport).

This perfect stage of self-realization is attained not by artificial means, but under the lotus feet of the Lord, who is always transcendental. In the Bhagavad-gītā the Lord says that He is present in everyone's heart, and from Him only all knowledge, remembrance or forgetfulness take place. When the living being desires to be an enjoyer of material energy (illusory phenomena), the Lord covers the living being in the mystery of forgetfulness, and thus the living being misinterprets the gross body and subtle mind to be his own self. And by culture of transcendental knowledge, when the living being prays to the Lord for deliverance from the clutches of forgetfulness, the Lord, by His causeless mercy, removes the living being's illusory curtain, and thus he realizes his own self. He then engages himself in the service of the Lord in his eternal constitutional position, becoming liberated from the conditioned life. All this is executed by the Lord either through His external potency or directly by the internal potency.
(Srimad Bhagavatam--1:3:33---purport).

To make the mind austere is to detach it from sense gratification. It should be so trained that it can be always thinking of doing good for others. The best training for the mind is gravity in thought. One should not deviate from Kṛṣṇa consciousness and must always avoid sense gratification. To purify one's nature is to become Kṛṣṇa conscious. Satisfaction of the mind can be obtained only by taking the mind away from thoughts of sense enjoyment. The more we think of sense enjoyment, the more the mind becomes dissatisfied. In the present age we unnecessarily engage the mind in so many different ways for sense gratification, and so there is no possibility of the mind's becoming satisfied. The best course is to divert the mind to the Vedic literature, which is full of satisfying stories, as in the Purāṇas and the Mahābhārata. One can take advantage of this knowledge and thus become purified. The mind should be devoid of duplicity, and one should think of the welfare of all. Silence means that one is always thinking of self-realization. The person in Kṛṣṇa consciousness observes perfect silence in this sense. Control of the mind means detaching the mind from sense enjoyment. One should be straightforward in his dealings and thereby purify his existence. All these qualities together constitute austerity in mental activities.
(Bhagavad-Gita---17:16---purport).

The activities of the day evoke dreams at night and induce emotions appropriate to those activities. Similarly, the activities performed in one's lifetime flash across one's mind at the moment of death and determine one's next life. Therefore, if one's present activities are directed toward chanting, hearing, and remembering the Supreme Lord's transcendental name, along with descriptions of His beauty, qualities, pastimes, associates, and paraphernalia, then one's consciousness at the moment one leaves his body will automatically be attracted to the Lord. Such a spiritual state of consciousness at the moment of death ensures the soul entry into the Supreme Lord's eternal abode in his very next birth. To awaken this spiritual consciousness is man's prime goal in life. We therefore find that Lord Kṛṣṇa, out of compassion for the conditioned souls, instructs Arjuna to fight and at the same time remember Him. This is called karma-yoga. Therefore devotees always remember Him in all their activities—in their endeavors for food and safety and even in the middle of the battlefield while fighting a war. Life being like a battlefield, in which one may die at any time, the devotees remember Him at every moment, and He willingly becomes the charioteer of their chariotlike bodies. The activities of their bodies, minds, and words are thus prompted by the Supreme Lord's will, and at the end, when they leave their gross and subtle bodies, they go directly to the spiritual sky.
(Renunciation Through Wisdom).