Best thing is that we should devote our life for awakening Kṛṣṇa consciousness. This human life is meant for that purpose. By nature's way, prakṛteḥ kriyamāṇāni guṇaiḥ karmāṇi sarvaśaḥ (BG 3.27), nature is bringing us. As soon as we become sinful, we are dropped down to suffer the sequence of sinful life in different varieties. Again, just like a man, criminal, is put into the jail, but when his term is finished, again he is made free. Similarly, the cycle of birth and death, dehāntara-prāptiḥ, tathā dehāntara-prāptiḥ (BG 2.13), one after another, is going on. So the animal life means reaction of sinful life, and upper class of life, demigods, means result of pious life. Two kinds of things are there, sinful and pious, through the cycle of birth is going on. But this human form of life or above human form of life, it is a chance for understanding the real value of life, and therefore for human beings there are guidances, these Vedas, Purāṇas, Vedānta-sūtra. It is meant for the human beings, not for the cats and dogs. Anādi-bahirmukha jīva kṛṣṇa bhuli gela ataeva kṛṣṇa veda-purāṇa kaila.
So it is recommended in the human form of life first of all training as a brahmacārī, then he may remain as gṛhastha for sometime. The life is divided into four parts, twenty-five years. Suppose I live a hundred years: twenty-five years to become brahmacārī, remain as brahmacārī; and twenty-five years to remain as gṛhastha, family man; and twenty-five years as vānaprastha; and twenty-five years as sannyāsa. This is system, Vedic system. Sannyāsa means.. vānaprastha is the preparation for sannyāsa, and sannyāsa means completely dedicated to the service of Kṛṣṇa. This is our system. Just like you are spirit soul. Our business is not here. Our business in the spiritual world. Here, by circumstances, you have fallen into the material condition, but if we take, "This is all-in-all our duty," that is not advised in the śāstra. It is circumstances. We have fallen into . . . under certain circumstances, so we have to take care of. The real duty is to how to save myself from this material entanglement.