“You should be most careful for your souls,” warns Deuteronomy 4:15. The rabbis took this to mean that we should not deliberately endanger our lives and health.
Applying the concept, Rabbi Ovadia Yosef and others have ruled that smoking is forbidden. Rabbi Eliezer Waldenberg (1915 – 2006) stipulated that if doctors decide that someone is too ill to fast on Yom Kippur, it is forbidden to do so.
This mitzvah is given in the context of Moses’s warnings against the temptations of idolatry. The Israeli rabbi and lawyer Aviad Hacohen draws a parallel between worshipping idols and relinquishing personal responsibility for our safety to health regulations. Health and safety tend to be over-regulated today, arguably to the point of being a kind of idolatory. But no set of guidelines can free us from being personally responsible for the decisions that we make and the risks we take.