In Bhagavad-gītā (18.61) it is said, īśvaraḥ sarva-bhūtānāṁ hṛd-deśe ’rjuna tiṣṭhati: “The Supreme Lord is situated in everyone’s heart, O Arjuna.” The living entity is within the body, and the Supersoul, the Supreme Personality of Godhead, is also there. He is called antaryāmī and caitya-guru. As Lord Kṛṣṇa states in Bhagavad-gītā (15.15), He is controlling everything:

sarvasya cāhaṁ hṛdi sanniviṣṭo
 mattaḥ smṛtir jñānam apohanaṁ ca

“I am seated in everyone’s heart, and from Me come remembrance, knowledge and forgetfulness.”

Everything is being directed by the Supersoul within the body; therefore the better part of valor is to take His direction and be happy. To take His directions, one needs to be a devotee, and this is also confirmed in Bhagavad-gītā (10.10):

teṣāṁ satata-yuktānāṁ
 bhajatāṁ prīti-pūrvakam
dadāmi buddhi-yogaṁ taṁ
 yena mām upayānti te

“To those who are constantly devoted and worship Me with love, I give the understanding by which they can come to Me.”

Although the Supersoul is in everyone’s heart (īśvaraḥ sarva-bhūtānāṁ hṛd-deśe ’rjuna tiṣṭhati), He talks only to the pure devotees who constantly engage in His service. In Caitanya-bhāgavata (Antya 3.45) it is said:

tāhāre se bali vidyā, mantra, adhyayana
 kṛṣṇa-pāda-padme ye karaye sthira mana

“One who has fixed his mind on the lotus feet of Kṛṣṇa is to be understood as having the best education and as having studied all the Vedas.” There are also other appropriate quotes in Caitanya-bhāgavata:

sei se vidyāra phala jāniha niścaya
 kṛṣṇa-pāda-padme yadi citta-vṛtti raya

“The perfect result of an education is the fixing of one’s mind on the lotus feet of Kṛṣṇa.” (Ādi 13.178)

‘dig-vijaya kariba,’ — vidyāra kārya nahe
 īśvare bhajile, sei vidyā ‘satya’ kahe

“Conquering the world by means of material education is not desirable. If one engages himself in devotional service, his education is perfected.” (Ādi 13.173)

paḍe kene loka — kṛṣṇa-bhakti jānibāre
 se yadi nahila, tabe vidyāya ki kare

“The purpose of education is to understand Kṛṣṇa and His devotional service. If one does not do so, then education is false.” (Ādi 12.49)

tāhāre se bali dharma, karma sadācāra
 īśvare se prīti janme sammata sabāra

“Being cultured, educated, very active and religious means developing natural love for Kṛṣṇa.” (Antya 3.44) Everyone has dormant love for Kṛṣṇa, and by culture and education that has to be awakened. That is the purpose of this Kṛṣṇa consciousness movement. Once Lord Caitanya asked Śrī Rāmānanda Rāya what the best part of education was, and Rāmānanda Rāya replied that the best part of education is advancement in Kṛṣṇa consciousness.