Every living being is searching after happiness, but no one knows where eternal and unlimited happiness is obtainable. Foolish men seek after material sense pleasure as a substitute for real happiness, but such foolish men forget that temporary so-called happiness derived from sense pleasures is also enjoyed by the dogs and hogs. No animal, bird or beast is bereft of this sense pleasure. In every species of life, including the human form of life, such happiness is immensely obtainable. The human form of life, however, is not meant for such cheap happiness. The human life is meant for attaining eternal and unlimited happiness by spiritual realization. This spiritual realization is obtained by tapasya, or undergoing voluntarily the path of penance and abstinence from material pleasure.

(Srimad Bhagavatam------1:3:13-------purport).

Material sense pleasures are due to the contact of the material senses, which are all temporary because the body itself is temporary. A liberated soul is not interested in anything which is temporary. Knowing well the joys of transcendental pleasures, how can a liberated soul agree to enjoy false pleasure? In the Padma Purāṇa it is said:
ramante yogino 'nante
satyānande cid-ātmani
iti rāma-padenāsau
paraṁ brahmābhidhīyate
(CC.2:9:29)
"The mystics derive unlimited transcendental pleasures from the Absolute Truth, and therefore the Supreme Absolute Truth, the Personality of Godhead, is also known as Rāma."

(Bhagavad-Gita------5:22------purport).

The spiritual values of life can be realized in the human form of material existence, and the human being must adopt family planning with reference to the context of spiritual values, and not otherwise. The degraded form of family restriction by use of contraceptives, etc., is the grossest type of material contamination. Materialists who use these devices want to fully utilize the pleasure potency of the coating on the genitals by artificial means, without knowing the spiritual importance. And without knowledge of spiritual values, the less intelligent man tries to utilize only the material sense pleasure of the genitals.

(Srimad Bhagavatam------2:6:8-------purport).

Śrī Yāmunācārya, a great devotee in Kṛṣṇa consciousness, said:
yad-avadhi mama cetaḥ kṛṣṇa-pādāravinde
nava-nava-rasa-dhāmany udyataṁ rantum āsīt
tad-avadhi bata nārī-saṅgame smaryamāne
bhavati mukha-vikāraḥ suṣṭhu niṣṭhīvanaṁ ca
"Since I have been engaged in the transcendental loving service of Kṛṣṇa, realizing ever-new pleasure in Him, whenever I think of sex pleasure I spit at the thought, and my lips curl with distaste." A person in brahma-yoga, or Kṛṣṇa consciousness, is so absorbed in the loving service of the Lord that he loses his taste for material sense pleasure altogether. The highest pleasure in terms of matter is sex pleasure. The whole world is moving under its spell, and a materialist cannot work at all without this motivation. But a person engaged in Kṛṣṇa consciousness can work with greater vigor without sex pleasure, which he avoids. That is the test in spiritual realization. Spiritual realization and sex pleasure go ill together. A Kṛṣṇa conscious person is not attracted to any kind of sense pleasure, due to his being a liberated soul.

(Bhagavad-Gita------5:21------purport).