B.G 3.20
karmaṇaiva hi saṁsiddhimāsthitā janakādayaḥ। lōkasaṅgrahamēvāpi sampaśyan kartumarhasi ॥20॥
Indeed, King Janaka and others could attain perfection and be in that state by performing prescribed duties alone. You are only eligible to perform your duties, having an eye towards the welfare of the world.
Gīta Tātparya 3.20
Sincerity towards attainment of knowledge is to perform activities as per the prescribed duties based on one's role in the society and phase of life. The ignorant must perform prescribed duties to gain knowledge. The knowledgeable must perform the prescribed duties for the welfare of the world.
sahaiva karmaṇā siddhimāsthitā janakādayaḥ। jñānaniṣṭhā api tataḥ kāryaṁ varṇāśramōcitam॥ iti ca।
King Janaka and others attained perfection by performing their respective duties. Therefore, sincerity towards attainment of knowledge is to perform activities as per the prescribed duties based on one's role in the society and phase of life (varna and ashrama). The testimonial also states the same:
ajñānāṁ jñānadaṁ karma jñānināṁ lōkasaṅgrahāt। addhaiva tuṣṭidaṁ mahyaṁ sā muktānandapūrtidā ॥20॥
"For the ignorant prescribed duties result in knowledge. For the knowledgeable, it promotes the welfare of the world. It is the giver of liberation, joy, and fulfillment and is immensely satisfying to me."
