(Prabhupada's lecture - Śrīmad-Bhāgavatam 2.1.3 – Delhi, November 6, 1973)
Prabhupāda: Vyavāyena ca vā vayaḥ. Vyavāya means sex life. So vyavāyena ca vā vayaḥ. The vayaḥ... Vayaḥ means duration of life. The more you indulge in sex life, your duration of life is reduced. That is the scientific method. Therefore the yogis, they give up sex life. It is a very great science, the breathing. During sex life there is more breathing. So the more you misuse your breathing, your duration of life is reduced. And if you can preserve this breathing, then you can increase your duration of life. Why people are dying nowadays, fifty years, sixty years, seventy years? No. One should live for at least hundred years. But because they unduly indulge in sex life, they die early. Their duration of life is reduced.
So these people, apaśyatām ātma-tattvam [SB 2.1.2], those who are ignorant of the ātma-tattvam, they indulge in nidrayā hriyate naktaṁ vyavāyena ca vā [SB 2.1.3]. This is their night's business. And day's business. What is the day's business? Divā cārthehayā rājan. During daytime, "Where is money? Where is money? Where is money? Where is money? Where is money? Go here, go there, go there, go... All right, take money. Then how to utilize it?" Now, kuṭumba-bharaṇena vā. 'Then go to the shop. Purchase this thing for my wife, for my children, for this, for that." So money earned and spent, and night, sleeping and mating. Then where is your time for cultivating Kṛṣṇa consciousness? This is the position. Apaśyatām ātma-tattvaṁ gṛheṣu gṛha-medhinām [SB 2.1.2]. Those who are blind, who do not know what is the value of this life, this human form of life, they are busy in these things. Apaśyatām ātma-tattvam [SB 2.1.2].