CC Madhya 11.37
yāhāṅ lañā yāya, tāhāṅ yāya jīva-rathī
Rāmānanda Rāya said, “The legs are like the chariot, and the heart is like the charioteer. Wherever the heart takes the living entity, the living entity is obliged to go.”
In the Bhagavad-gītā (18.61) Lord Kṛṣṇa explains:
bhrāmayan sarva-bhūtāni yantrārūḍhāni māyayā
“The Supreme Lord is situated in everyone’s heart, O Arjuna, and is directing the wanderings of all living entities, who are seated as on a machine made of material energy.”
Thus the living entity wanders within this universe riding upon a chariot (the body) bestowed by material nature. A similar explanation is given in the Kaṭha Upaniṣad (1.3.3-4):
buddhiṁ tu sārathiṁ viddhi manaḥ pragraham eva ca
ātmendriya-mano-yuktaṁ bhoktety āhur manīṣiṇaḥ
Here it is said that the living entity is the passenger riding in the chariot of the body, which is offered by material nature. The intelligence is the charioteer, the mind constitutes the reins controlling the horses, and the senses are the horses. Thus the living entity is the false enjoyer of the material world.
One who is advanced in Kṛṣṇa consciousness can control the mind and intelligence and in this way rein in the horses, the senses, even though they are very powerful. One who can control the senses by his mind and intelligence can very easily approach the Supreme Personality of Godhead, or Viṣṇu, who is the ultimate goal of life. Tad viṣṇoḥ paramaṁ padaṁ sadā paśyanti sūrayaḥ. Those who are actually advanced approach Lord Viṣṇu, their ultimate goal. Such people are never captivated by Lord Viṣṇu’s external energy, the material world.