Spiritual life begins when a person understands that he is not the body. In the material world, all our connections—whether social or political or in the field of eating, sleeping, defending, and mating—are due only to the material body. Unless one is completely conversant with the fact that one is not the body, it is not possible to become self-realized.
In the Bhagavad-gītā (18.54), Lord Kṛṣṇa describes self-realization as follows:
brahma-bhūtaḥ prasannātmā na śocati na kāṅkṣati
samaḥ sarveṣu bhūteṣu mad-bhaktiṁ labhate parām
"Self-realization [the brahma-bhūta [SB 4.30.20] stage] is symptomized by joyfulness. One never laments for any loss, nor is one very enthusiastic when there is some gain. One sees everyone on an equal level through spiritual understanding. These qualities are preliminary to entering into pure devotional service."
Pure devotional service is so powerful, however, that one may at once take to it without acquiring the previous qualification of brahma-bhūta life. A sincere devotee who engages in the service of the Lord automatically becomes situated in the brahma-bhūta stage. The devotee's duty is only to strictly follow the principles of regulated devotional service, as previously mentioned. Therefore a devotee should not be too concerned about social and political obligations, since all such activities belong to the body. He should similarly restrict his eating; this is essential to the execution of devotional service. A devotee cannot eat anything and everything he likes; he must eat only foods that have been offered to the Lord. The Lord clearly says (Bhagavad-gītā 9.26) that He will accept a flower, a fruit, a leaf, or a little water if they are offered to Him with devotional love. (One should note that the Supreme Lord accepts only foods from the vegetable kingdom, as well as milk products. "Water" includes milk and its products.) The Lord is not hungry or poor, in need of our offering. Actually, it is to our advantage to offer Him something to eat. If the Supreme Lord kindly accepts our offering, then we are benefited. The Lord is full, but to establish the universal principle that everyone can offer something to the Lord, He accepts even the most meager offering—when it is presented with love. Even the poorest of the poor can collect a flower, a leaf, and a little water and offer them to the Supreme Lord.
It is incumbent upon all devotees of Kṛṣṇa to avoid eating anything that has not been offered to the Supreme Lord. A devotee who does not strictly follow this principle is sure to fall down. Similarly, one who refuses to accept prasādam, the remnants of food offered to Kṛṣṇa, cannot become a devotee.
In the Śrīmad-Bhāgavatam (5.5.3) Lord Ṛṣabhadeva states that one who is determined to become a pure devotee avoids associating with the general mass of people, who are simply engaged in the animal propensities of eating, sleeping, defending, and mating. The general mass of people mistake the body for the self, and therefore they are always busy trying to maintain the body very nicely. A devotee should not associate with such people. Nor should he be overly attached to his family members, knowing that he has been accidentally thrown together with his wife, children, and so on. Spiritually, no one is a wife, child, husband, or father of anyone else. Everyone comes into this world according to his past deeds and takes shelter of a father and a mother, but actually no one is anyone's father or mother. While a devotee must know this, that does not mean he should neglect his family. As a matter of duty he should maintain his family members without attachment and instruct them in Kṛṣṇa consciousness.
So, whether in social life or political life, or in the matter of eating, sleeping, mating, and defending, a devotee should avoid performing any action tainted by material attachment. The word used here is bhojanādi, which indicates the four propensities of eating, sleeping, defending, and mating. As the devotee does not eat anything that has not been offered to Kṛṣṇa, so he does not sleep more than is absolutely necessary. In the lives of the great devotees Sanātana Gosvāmī and Rūpa Gosvāmī, we see that they did not sleep more than one and a half hours a day, and they were reluctant even to accept that. So sleeping is also restricted. Naturally one who is always engaged in devotional service of the Lord has very little time to sleep. Sleep is a necessity of the body, not the spirit soul, and therefore as one advances in devotional service one's propensity to sleep decreases.
Similarly, a devotee minimizes his defending propensity. A pure devotee knows he is under the shelter of the all-powerful Supreme Lord, and so he is not very anxious about defending himself. Although he should use his common sense in the matter of defending, he is sure that without being protected by Lord Kṛṣṇa no one can defend himself, however expert he may be in the art of defense.
In the same way, a devotee minimizes or eliminates sex. He does not indulge indiscriminately in sex, begetting offspring as the cats and dogs do. If he begets any children at all, he takes charge of them to elevate them to Kṛṣṇa consciousness so that they may not have to suffer in material life again, in future lives. That is the duty of a devotee.
In this material world, people in general engage in sense-gratificatory activities, which keep them bound up by the laws of the material modes of nature. Indeed, the more a person engages in such activities, the more he expands his life in material existence. A devotee acts differently: he knows he is not the body and that as long as he is in his body he will have to suffer the threefold material miseries. Therefore to decrease his material entanglement and help his advancement in spiritual life, he always minimizes his social and political activities and his eating, sleeping, defending, and mating.