Is self-defense mandatory for a Muslim?

According to the Qur'an, does a Muslim **have to** defend himself against attacks by other people or illness (aka "value his life") or is it a "I don't have a problem if you do it"-mentality. Like: I don't punish you if you defend yourself, but if you don't, I don't care? In other words: Is there a part in the Qur'an that says "I will punish you, if you don't care for your body. If you don't defend your body from illness and attacks, you'll go to hell". (Also in case of taking drugs)