Kṛṣṇa tells Arjuna that he should act in yoga. And what is that yoga? Yoga means to concentrate the mind upon the Supreme by controlling the ever-disturbing senses. And who is the Supreme? The Supreme is the Lord. And because He Himself is telling Arjuna to fight, Arjuna has nothing to do with the results of the fight. Gain or victory are Kṛṣṇa's concern; Arjuna is simply advised to act according to the dictation of Kṛṣṇa. The following of Kṛṣṇa's dictation is real yoga, and this is practiced in the process called Kṛṣṇa consciousness. By Kṛṣṇa consciousness only can one give up the sense of proprietorship. One has to become the servant of Kṛṣṇa, or the servant of the servant of Kṛṣṇa [Cc. Madhya 13.80]. That is the right way to discharge duty in Kṛṣṇa consciousness, which alone can help one to act in yoga. Arjuna is a kṣatriya, and as such he is participating in the varṇāśrama-dharma institution. It is said in the Viṣṇu Purāṇa that in the varṇāśrama-dharma, the whole aim is to satisfy Viṣṇu. No one should satisfy himself, as is the rule in the material world, but one should satisfy Kṛṣṇa. So unless one satisfies Kṛṣṇa, one cannot correctly observe the principles of varṇāśrama-dharma. Indirectly, Arjuna was advised to act as Kṛṣṇa told him.
(Bhagavad-Gita----2:48----purport).

To say that one is in samādhi is to say that one has fully realized Kṛṣṇa consciousness; that is, one in full samādhi has realized Brahman, Paramātmā and Bhagavān. The highest perfection of self-realization is to understand that one is eternally the servitor of Kṛṣṇa and that one's only business is to discharge one's duties in Kṛṣṇa consciousness. A Kṛṣṇa conscious person, or unflinching devotee of the Lord, should not be disturbed by the flowery language of the Vedas nor be engaged in fruitive activities for promotion to the heavenly kingdom. In Kṛṣṇa consciousness, one comes directly into communion with Kṛṣṇa, and thus all directions from Kṛṣṇa may be understood in that transcendental state. One is sure to achieve results by such activities and attain conclusive knowledge. One has only to carry out the orders of Kṛṣṇa or His representative, the spiritual master.
(Bhagavad-Gita----2:53----purport).

A pure soul is the eternal servant of God as His fragmental part and parcel. He comes into contact with māyā (illusion) due to the desire to lord it over māyā, and that is the cause of his many sufferings. As long as he is in contact with matter, he has to execute work in terms of material necessities. Kṛṣṇa consciousness, however, brings one into spiritual life even while one is within the jurisdiction of matter, for it is an arousing of spiritual existence by practice in the material world. The more one is advanced, the more he is freed from the clutches of matter. The Lord is not partial toward anyone. Everything depends on one's practical performance of duties in Kṛṣṇa consciousness, which helps one control the senses in every respect and conquer the influence of desire and anger. And one who stands fast in Kṛṣṇa consciousness, controlling the abovementioned passions, remains factually in the transcendental stage, or brahma-nirvāṇa. The eightfold yoga mysticism is automatically practiced in Kṛṣṇa consciousness because the ultimate purpose is served. There is a gradual process of elevation in the practice of yama, niyama, āsana, prāṇāyāma, pratyāhāra, dhāraṇā, dhyāna and samādhi. But these only preface perfection by devotional service, which alone can award peace to the human being. It is the highest perfection of life.
(Bhagavad-Gita----5:29----purport).

Extravagance in the matter of eating, sleeping, defending and mating—which are demands of the body—can block advancement in the practice of yoga. As far as eating is concerned, it can be regulated only when one is practiced to take and accept prasādam, sanctified food. Lord Kṛṣṇa is offered, according to the Bhagavad-gītā (9.26), vegetables, flowers, fruits, grains, milk, etc. In this way, a person in Kṛṣṇa consciousness becomes automatically trained not to accept food not meant for human consumption, or not in the category of goodness. As far as sleeping is concerned, a Kṛṣṇa conscious person is always alert in the discharge of his duties in Kṛṣṇa consciousness, and therefore any unnecessary time spent sleeping is considered a great loss. Avyartha-kālatvam: [Cc. Madhya 23.18-19] a Kṛṣṇa conscious person cannot bear to pass a minute of his life without being engaged in the service of the Lord. Therefore, his sleeping is kept to a minimum. His ideal in this respect is Śrīla Rūpa Gosvāmī, who was always engaged in the service of Kṛṣṇa and who could not sleep more than two hours a day, and sometimes not even that. Ṭhākura Haridāsa would not even accept prasādam nor even sleep for a moment without finishing his daily routine of chanting with his beads three hundred thousand names. As far as work is concerned, a Kṛṣṇa conscious person does not do anything which is not connected with Kṛṣṇa's interest, and thus his work is always regulated and is untainted by sense gratification. Since there is no question of sense gratification, there is no material leisure for a person in Kṛṣṇa consciousness. And because he is regulated in all his work, speech, sleep, wakefulness and all other bodily activities, there is no material misery for him.
(Bhagavad-Gita----6:17----purport).

As long as the material body exists, one has to meet the demands of the body, namely eating, sleeping, defending and mating. But a person who is in pure bhakti-yoga, or in Kṛṣṇa consciousness, does not arouse the senses while meeting the demands of the body. Rather, he accepts the bare necessities of life, making the best use of a bad bargain, and enjoys transcendental happiness in Kṛṣṇa consciousness. He is callous toward incidental occurrences—such as accidents, disease, scarcity and even the death of a most dear relative—but he is always alert to execute his duties in Kṛṣṇa consciousness, or bhakti-yoga. Accidents never deviate him from his duty. As stated in the Bhagavad-gītā (2.14), āgamāpāyino 'nityās tāṁs titikṣasva bhārata. He endures all such incidental occurrences because he knows that they come and go and do not affect his duties. In this way he achieves the highest perfection in yoga practice.
(Bhagavad-Gita----6:20-23----purport).

The next question concerns the dealings of a transcendentally situated person. The materially situated person is affected by so-called honor and dishonor offered to the body, but the transcendentally situated person is not affected by such false honor and dishonor. He performs his duty in Kṛṣṇa consciousness and does not mind whether a man honors or dishonors him. He accepts things that are favorable for his duty in Kṛṣṇa consciousness, otherwise he has no necessity of anything material, either a stone or gold. He takes everyone as his dear friend who helps him in his execution of Kṛṣṇa consciousness, and he does not hate his so-called enemy. He is equally disposed and sees everything on an equal level because he knows perfectly well that he has nothing to do with material existence. Social and political issues do not affect him, because he knows the situation of temporary upheavals and disturbances. He does not attempt anything for his own sake. He can attempt anything for Kṛṣṇa, but for his personal self he does not attempt anything. By such behavior one becomes actually transcendentally situated.
(Bhagavad-Gita----14:22-25----purport).

Although fire is pure, still there is smoke. Yet smoke does not make the fire impure. Even though there is smoke in the fire, fire is still considered to be the purest of all elements. If one prefers to give up the work of a kṣatriya and take up the occupation of a brāhmaṇa, he is not assured that in the occupation of a brāhmaṇa there are no unpleasant duties. One may then conclude that in the material world no one can be completely free from the contamination of material nature. This example of fire and smoke is very appropriate in this connection. When in wintertime one takes a stone from the fire, sometimes smoke disturbs the eyes and other parts of the body, but still one must make use of the fire despite disturbing conditions. Similarly, one should not give up his natural occupation because there are some disturbing elements. Rather, one should be determined to serve the Supreme Lord by his occupational duty in Kṛṣṇa consciousness. That is the perfectional point. When a particular type of occupation is performed for the satisfaction of the Supreme Lord, all the defects in that particular occupation are purified. When the results of work are purified, when connected with devotional service, one becomes perfect in seeing the self within, and that is self-realization.
(Bhagavad-Gita----18:48----purport).

In Bhagavad-gītā (2.14), Kṛṣṇa advises that one be tolerant: tāṁs titikṣasva bhārata. Following this advice of Kṛṣṇa's, one should not be morose or unhappy because of circumstantial changes. This is the symptom of a devotee. A devotee carries out his duty in Kṛṣṇa consciousness and is never unhappy in awkward circumstances. He has full faith that in such circumstances, Kṛṣṇa protects His devotee. Therefore a devotee never deviates from his prescribed duty of devotional service.
(Srimad Bhagavatam----8:11:8----purport).

Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura says that if an observer immediately remembers the holy name of Kṛṣṇa upon seeing a Vaiṣṇava, that Vaiṣṇava should be considered a mahā-bhāgavata, a first-class devotee. Such a Vaiṣṇava is always aware of his Kṛṣṇa conscious duty, and he is enlightened in self-realization. He is always in love with the Supreme Personality of Godhead, Kṛṣṇa, and this love is without adulteration.
(Sri Caitanya Caritamrta----2:16:74----purport).

A devotee who is not perfectly freed from the resultant actions should therefore continue to act in Kṛṣṇa consciousness seriously, even though there may be so many impediments. When such impediments arise he should simply think of Kṛṣṇa and expect His mercy. That is the only solace. If the devotee passes his days in that spirit, it is certain that he is going to be promoted to the abode of the Lord. By such activities, he earns his claim to enter into the kingdom of God. The exact word used in this verse is dāya-bhāk. Dāya-bhāk refers to a son's becoming the lawful inheritor of the property of the father. In a similar way, a pure devotee who is prepared to undergo all kinds of tribulations in executingKṛṣṇa conscious duties becomes lawfully qualified to enter into the transcendental abode.
(Nectar of Devotion).