As I stated in the introduction to this chapter, the Rambam's fourth chapter is devoted almost entirely to health issues. As we saw earlier, the Ramban views maintaining one's health as a religious obligation; accordingly, he devoted a chapter of his work to medical advice. Although a fair measure of his advice is archaic, I decided for completeness' sake to translate this chapter in its entirety, offering virtually no comments of my own.
 One should not accustom himself to bloodletting constantly. He should only let blood if he especially needs it. He should not let blood in the summer or the rainy season, but in the springtime and a little in the fall. Beyond the age of 50, he should not let blood at all.
One should not let blood and enter the bathhouse on the same day. He should [also] not let blood and [then] travel, nor should he let blood on the day he returns from travel.
One should eat and drink less than usual on the day of his bloodletting. He should rest on that day, neither exerting himself nor walking.
 Semen is the strength of a person's body, his life, and the light of his eyes. Whenever too much of it goes out, his body withers, his strength wanes and his life expires (lit., "is lost"). This is what Solomon said in his wisdom, "Do not give your strength to women nor your ways to that which blots out kings" (Proverbs 31:3). Any one who is obsessed (lit., "carried away") with sex will age rapidly (lit., "old age will jump upon him"), his strength will weaken, his eyes will dim, a bad smell will emanate from from his mouth and underarms, the hair of his head, eyebrows and eylashes will fall out, the hair of his beard, underarms and his legs will increase, his teeth will fall out, and many ailments besides these will afflict him.
Doctors say that one out of a thousand dies from other ailments, whereas a thousand from too much sex. Therefore, one should be careful in this matter if he wants to live well. He should not have relations except when his body is healthy and very strong. If a person finds he has many unintentional erections even when he thinks about other matters, and he feels heavy in his loins and below, and the cords of his testicles feel stretched and his flesh warm -- such a person should have relations and this is healthful for him.
One should not have relations when he is full or hungry, but rather after his food is digested. He should check that he does not need the bathroom both before and after having relations. He should not have relations standing or sitting, nor in the bathhouse, nor on the day that he goes to the bathhouse, nor on the day he lets blood, nor on the day he intends to travel, nor on the day he returns from travel, nor on the day before or after he travels.
 Anyone who accustoms himself in these ways that we have taught, I guarantee him that he will not come to sickness his entire life -- so much so that he will live long (lit. "age greatly") and die without requiring a doctor. His body will be whole and healthy his entire life -- unless he was created with a defective (lit., "bad") body, he accustomed himself with one of the bad health practices [described earlier] from his birth, or if a plague or famine comes to the world.
 All of these good habits which we have discussed are only applicable to a healthy person. One, however, who is sick or one of his limbs is ailing, or one who formerly had an unhealthy lifestyle (lit., "who accustomed himself to a bad practice for many years"), it is appropriate for each of them to follow different ways according to his ailment, as explained in books of medicine. For changing one's regular pattern is the start of illness.
 Wherever there is no doctor, both the healthy and sick person should adhere to the ways we have described in this chapter, for all of these ways ultimately lead to good health (lit., "bring to good").
 Any city which does not have the following ten things a Torah scholar should not dwell in. They are: a doctor, a bloodletter, a bathhouse, a bathroom (meaning, a sheltered outhouse), a ready supply of water such as a river or stream, a synagogue, a teacher of children, a scribe, a custodian of the charity collections ("gabbai tzedaka"), and a court which both administers corporal punishment (lit., "hits") and jails.