Regulated sex life to generate good population is worth accepting. Actually, Vidura was not interested in hearing the history of persons who merely engaged in sex life, but he was interested in the progeny of Svāyambhuva Manu because in that dynasty, good devotee kings appeared who protected their subjects very carefully with spiritual knowledge. By hearing the history of their activities, therefore, one becomes more enlightened. An important word used in this connection is parama-sammataḥ, which indicates that the progeny created by Svāyambhuva Manu and his sons was approved of by great authorities. In other words, sex life for creating exemplary population is acceptable to all sages and authorities of Vedic scripture.
(Srimad Bhagavatam--------3:21:1-------purport).

People addicted to householder life wonder how one can give up the enjoyment of gṛhastha life, which is a concession for sex enjoyment, simply to become a mendicant in Kṛṣṇa consciousness. They do not know that the householder's concession for sex life cannot be regulated unless one accepts the life of a mendicant. The Vedic civilization therefore enjoins that at the end of one's fiftieth year one must give up household life. This is compulsory. However, because modern civilization is misled, householders want to remain in family life until death, and therefore they are suffering.
(Srimad Bhagavatam--------6:5:36-------purport).

In this verse it is clear that both kinds of senses, the senses for acquiring knowledge and the senses for action, are products of egoism in the mode of passion. And because the sense organs for activity and for acquiring knowledge require energy, the vital energy, or life energy, is also produced by egoism in the mode of passion. We can actually see, therefore, that those who are very passionate can improve in material acquisition very quickly. It is recommended in the Vedic scriptures that if one wants to encourage a person in acquiring material possessions, one should also encourage him in sex life. We naturally find that those who are addicted to sex life are also materially advanced because sex life or passionate life is the impetus for the material advancement of civilization. For those who want to make spiritual advancement, there is almost no existence of the mode of passion. Only the mode of goodness is prominent.
(Srimad Bhagavatam--------3:26:31-------purport).

A brahmacārī practices celibacy, controlling his sex life. One cannot enjoy unrestricted sex life and practice yoga; this is rascaldom. So-called yogīs advertise that one can go on enjoying as one likes and simultaneously become a yogī, but this is totally unauthorized. It is very clearly explained here that one must observe celibacy. Brahmacaryam means that one leads his life simply in relationship with Brahman, or in full Kṛṣṇa consciousness. Those who are too addicted to sex life cannot observe the regulations which will lead them to Kṛṣṇa consciousness. Sex life should be restricted to persons who are married. A person whose sex life is restricted in marriage is also called a brahmacārī.
(Srimad Bhagavatam--------3:28:4-------purport).

Generally, people are concerned with the satisfaction of the tongue and the satisfaction of the genitals. That is material life. Material life means eat, drink, be merry and enjoy, with no concern for understanding one's spiritual identity and the process of spiritual advancement. Since materialistic people are concerned with the tongue, belly and genitals, if anyone wants to advance in spiritual life he must be very careful about associating with such people. To associate with such materialistic men is to commit purposeful suicide in the human form of life. It is said, therefore, that an intelligent man should give up such undesirable association and should always mix with saintly persons. When he is in association with saintly persons, all his doubts about the spiritual expansion of life are eradicated, and he makes tangible progress on the path of spiritual understanding. It is also sometimes found that people are very much addicted to a particular type of religious faith. Hindus, Muslims and Christians are faithful in their particular type of religion, and they go to the church, temple or mosque, but unfortunately they cannot give up the association of persons who are too much addicted to sex life and satisfaction of the palate. Here it is clearly said that one may officially be a very religious man, but if he associates with such persons, then he is sure to slide down to the darkest region of hell.
(Srimad Bhagavatam--------3:31:32-------purport).

Those who are too addicted to sex life cannot understand the purpose of the Absolute Truth, nor can they be clean in their habits, not to mention showing mercy to others. They cannot remain grave, and they have no interest in the ultimate goal of life. The ultimate goal of life is Kṛṣṇa, or Viṣṇu, but those who are addicted to sex life cannot understand that their ultimate interest is Kṛṣṇa consciousness. Such people have no sense of decency, and even in public streets or public parks they embrace each other just like cats and dogs and pass it off in the name of love-making. Such unfortunate creatures can never become materially prosperous. Behavior like that of cats and dogs keeps them in the position of cats and dogs. They cannot improve any material condition, not to speak of becoming famous. Such foolish persons may even make a show of so-called yoga, but they are unable to control the senses and mind, which is the real purpose of yoga practice. Such people can have no opulence in their lives. In a word, they are very unfortunate.
(Srimad Bhagavatam--------3:31:33-------purport).