By His Divine Grace A.C. Bhaktivedanta Swami Prabhupada
Since we have got this body in this material world, we have to maintain it. That is necessary because this is not the spiritual world. In the spiritual world, there is no necessity of maintaining the body since the body is spiritual. Here, in the material world, in order to maintain this body I require to eat, I require to sleep, I require to satisfy my senses and I require to defend. These are the four necessities: āhāra-nidrā-bhaya-maithunam ca. In the spiritual body these four kinds of bodily demands do not remain anymore. That is spiritual life. That means no eating, no sleeping, no sex, and no defense. The six Gosvāmīs of Vrindāvana practiced it. nidrāhāra-vihārakādi-vijitau: they conquered over sleeping, eating, mating, and defending. Nidrā means sleeping, āhāra means eating, vihāra means sex and vijitau means conquered.So this is the advancement of spiritual life. When we conquer over these things, it means we have come to the spiritual platform. So long we have got this material body, although it is not possible, we should try to minimize.