We should be very, very careful that this human form of life should not be wasted even for a moment. That is real life. There is, by…, one sloka by Rupa Gosvami, avyartha-kalatvam [Cc. Madhya 23.18-19]. A devotee should always be alert to see, “Whether this time, one moment passed, whether I have wasted it or I have utilized it?” That is, should be, the point. Ayusah ksana eko ‘pi na labhya svarna-kotibhih [Canakya-sloka 34]. This is also material estimation, that one moment of our life cannot be returned in exchange of millions of dollars, even from material point of view. And those who are advancing in spiritual life, how much careful they should be. Therefore Rupa Gosvami has given the formula, avyartha-kalatvam. Not a single moment may be wasted without chanting Hare Krsna.

From Srila Prabhupada’s lecture on Srimad-Bhagavatam 5.5.16 — November 4, 1976, Vrndavana