This probably covers the issue of overindulgence.
Excerpt from Grandmasters 152nd book:
Chapter 3: Living this Moment of Illumination, The Words of the Fire Deity:
"According to my knowledge, the human body is not made of gold, silver, copper, and iron: it is made of energy, blood, essence, and bone. Even between couples, one needs to restrain one's sexual desires.
One's energy and blood run through six blood vessels. It takes one entire day to circulate though one vessel, and six days in total to circulate through all six vessels.
The six blood vessels are named: T'ai-yang, Yang-ming, Shao-yin, T'ai-yin, Shao-yin, and Chueh-yin.
The completion of a circulation through all six blood vessels is called one complete cycle of circulation of energy and blood.
When one craves sex, one's heart leaps and one's body sweats. The body temperature rises and one loses mental control. As a result, the joints open, the nerves and vessels become depleted, and one's essence flows out.
When one blood vessel is depleted, it requires seven days for it to recover. This is termed, "seven days of recovery", meaning that one has to rest for seven days. If a couple's sex life is excessive and the frequency of their sexual intercourse is less than seven days, then they lose their essence and blood too often, and eventually are unable to recover their depletion of blood vessels and energy.
Therefore, the sages of long ago set up a regulation of restraining from having excessive sex in order to remain healthy:
* When twenty years old, one's standard sex life should not exceed once every seven days.
* When thirty years old, one's standard sex life should not exceed once every fourteen days.
* When forty years old, one's standard sex life should not exceed once every twenty-eight days.
* When fifty years old, one's standard sex life should not exceed once every forty-five days.
* When sixty years old, one's blood vessels can no longer be recovered.
If ordinary couples do not restrain their sex life, believing that it's harmless to engage in excessive sex as they are still young, then day-by-day they will suffer the loss of strength and resource. Six blood vessels become depleted, energy and blood dissolve, essence withers, and many illnesses are generated. One would have an early death!"
http://www.padmakumara.org/books/book152/chap3.shtml