Yogis and transcendentalists who want to live for greater spans of life voluntarily restrain themselves from discharging semen. The more one can restrain the discharge of semen, the more one can be aloof from the problem of death. There are many yogis living up to three hundred or seven hundred years by this process, and in the Bhagavatam it is clearly stated that discharging semen is the cause of horrible death. The more one is addicted to sexual enjoyment, the more susceptible he is to a quick death.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Third Canto, Chapter 26 – Text 57