The Need to be Healthy

It is commonly assumed that the mitzva to take proper safety precautions is based on the Passuk in Ve’eschanan,“Vinishmartem meod linafshoseichem- You shall be exceedingly careful with you nefesh” (Devarim 4;15). However, the rest of the Passuk is a clear warning against idolatry. If so, it would seem that this Passuk does not refer to the mitzvah to protect one's physical body but rather a commandment to take the necessary precautions to ensure that the Jews would not worship idols once entering Eretz Yisroel. 

In fact, the Rambam in (Sefer Hamitzvos Aseh 184) writes that the mitzvah to protect one’s physical well-being is derived from the mitzvah to erect a fence around one’s roof. The message behind this mitzvah is to remove any physical dangers from our properties, which certainly obligates us to refrain from dangerous behavior ourselves. However, the Rambam (Rotzeich 11 4-5) quotes a similar passuk (Devarim 4;9) as the source to remove physical dangers. However, based on the previous Rambam and the Pessukim themselves, it would seem that the Rambam is ignoring the simple reading of the Passuk. 

The Chofetz Chaim (Shem Olam 2:10) explains that one should approach everything he does as a part of his heavenly mission to this world. Of course, this applies to one’s Torah and mitzvos, but even physical acts and needs must be addressed with the sole focus of improving one’s ability to serve Hashem. The Chofetz Chaim explains that this is why the Torah refers to our nefesh when telling us to watch our bodies- because the real reason we must care for our physical needs is a means for our spiritual ones. With this perspective, we understand the obligation to give up one's life to avoid transgressing one of the three cardinal sins (idolatry, murder, and adultery). While one is supposed to transgress most mitzvos to save their life, this is only as a means to perform more mitzvos. However, these cardinal sins are so integral to life as a Jew that one cannot transgress them so that one can be able to do more mitzvos.