We work not with our body, actually, but with our mind and intelligence. So if the intelligence and the mind are always engaged in the thought of the Supreme Lord, then naturally the senses are also engaged in His service. Superficially, at least, the activities of the senses remain the same, but the consciousness is changed. The Bhagavad-gītā teaches one how to absorb the mind and intelligence in the thought of the Lord. Such absorption will enable one to transfer himself to the kingdom of the Lord. If the mind is engaged in Kṛṣṇa's service, then the senses are automatically engaged in His service. This is the art, and this is also the secret of Bhagavad-gītā: total absorption in the thought of Śrī Kṛṣṇa.
(Bhagavad-Gita---introduction).

If, therefore, the soul is directly engaged with the Supreme, naturally all other subordinates, namely, the intelligence, mind and senses, will be automatically engaged. In the Kaṭha Upaniṣad there is a similar passage, in which it is said that the objects of sense gratification are superior to the senses, and mind is superior to the sense objects. If, therefore, the mind is directly engaged in the service of the Lord constantly, then there is no chance that the senses will become engaged in other ways. This mental attitude has already been explained. paraṁ dṛṣṭvā nivartate. If the mind is engaged in the transcendental service of the Lord, there is no chance of its being engaged in the lower propensities. In the Kaṭha Upaniṣad the soul has been described as mahān, the great. Therefore the soul is above all-namely, the sense objects, the senses, the mind and the intelligence. Therefore, directly understanding the constitutional position of the soul is the solution of the whole problem.
(Bhagavad-Gita----3:42---purport).

With intelligence one has to seek out the constitutional position of the soul and then engage the mind always in Kṛṣṇa consciousness. That solves the whole problem. A neophyte spiritualist is generally advised to keep aloof from the objects of the senses. But aside from that, one has to strengthen the mind by use of intelligence. If by intelligence one engages one's mind in Kṛṣṇa consciousness, by complete surrender unto the Supreme Personality of Godhead, then, automatically, the mind becomes stronger, and even though the senses are very strong, like serpents, they will be no more effective than serpents with broken fangs. But even though the soul is the master of intelligence and mind, and the senses also, still, unless it is strengthened by association with Kṛṣṇa in Kṛṣṇa consciousness, there is every chance of falling down due to the agitated mind.
(Bhagavad-Gita----3:42---purport).

Knowing oneself to be transcendental to the material senses, mind and intelligence, one should steady the mind by deliberate spiritual intelligence (Kṛṣṇa consciousness) and thus—by spiritual strength-conquer this insatiable enemy known as lust.
(Bhagavad-Gita----3:43---purport).

With your activities dedicated to Me (Kṛṣṇa) and your mind and intelligence fixed on Me, you will attain Me without doubt.
(Bhagavad-Gita----8:7---purport).

If one is absorbed in thoughts of the Supreme Lord Śrī Kṛṣṇa, he is sure to go back to Godhead without any doubt. This is confirmed in the Bhagavad-gītā: "With your activities dedicated to Me and your mind and intelligence fixed on Me, you will attain Me without doubt."
(Srimad Bhagavatam----1:9:30----purport).

The pure devotee, simply by remembering the Lord's lotus feet at every second, at once becomes established in real trance because by such realization his mind and intelligence are completely cleansed of the diseases of material enjoyment.
(Srimad Bhagavatam----2:4:21----purport).

It does not matter what one is, whether a brāhmaṇa, kṣatriya, vaiśya, śūdra or a degraded woman. If one engages himself seriously in devotional service, working with body, mind and intelligence, he is sure to be successful in going back home, back to Godhead.
(Srimad Bhagavatam----2:21:33----purport).