Swami Sivananda : A sexual act shatters the nervous system. The whole nervous system is shaken or Agitated during the act. There is Excessive loss of energy. More energy is wasted during coition. But it is not so when emission occurs during the dreaming state. In a wet dream, It May be the outflow of the prostatic juice only. Even if there is loss of the vital fluid, there is not much draining. The actual essence does not come out during wet dreams.  It is only the water prostatic juice with a little seed that is discharged during nocturnal pollutions. (Swamijee was himself a doctor before embracing sannyasa)

Saint Kabir : Just after the act, both the partners feel extreme drainage of energy, still no one understands the importance of celibacy.

Guru Nanaka : Those who waste the fluid are tyrannized by Kal [the negative power]. Those who waste the fluid lose all. Those who waste the fluid suffer greatly ... He who wastes the fluid always suffers. Those who waste the fluid suffer greatly...He who wastes the fluid gets into extreme troubles ... He who does not control the fluid is degraded .... By self control one gets everything. He who wastes the fluid gets into extreme troubles...He who does not control the fluid is degraded....By self control one gets everything. - From "Pran Sangli" of Guru Nanak

Lord Buddha : A wise man should avoid unchastity as if it were a burning pit of live coals. From the contact comes sensation, from sensation thirst, from thirst clinging; by ceasing from that, the soul is delivered from all Sinful existence.

Lord Krishna: Sensuality destroys life, luster, strength, vitality, memory, wealth, great fame, holiness and devotion to the Supreme.  - From Gita.

Adi Guru Sankaracharya : Brahmacharya or spotless chastity is the best of all penances; a celibate of such spotless chastity is not a human being, but a god indeed... To the celibate who conserves the seeds with great Efforts, what there is unattainable in this world? By the power of the Composure of the seeds, one will become just like myself.

Ramakrishna Paramahansa: The whole progress in raising the kundalini shakti along the sushumna nadi (for attaining God-Realization) through spiritual sadhana of two whole years is fully wasted seeds in losing just once. - From "The Gospel of Ramakrishna Paramahansa"

Sant Shri Asaramji Bapu : Vital Energy is the essence of Your Body. Preservation of it is the key to longevity of youthfulness.Throughout history, great sages, saints, and seers have stressed the paramount importance of celibacy for leading a noble and sublime life. A person lacking in self-restraint and self-discipline can never make progress in any worthwhile endeavor nor can he be of any service to the society. A society made up of dry people is unable to make any material or spiritual progress. Such degenerated societies Disintegrate in the long run.

Jesus Christ : For there are some eunuchs, which were so born from their mother's womb; there are some eunuchs of men; and there be eunuchs, which made themselves eunuchs for the kingdom of heaven's sake. That He is Able to receive let him receive.