In fact, Orthodox Judism REQUIRES that you do nothing that would harm yourself in following "the rules." For instance, if you're on medication that is required for your health, like blood pressure medicine, then you're required to take it properly, even on a fast day. And the Orthodox prohibition of driving is waved in case of an emergency. Depending on the situation, "bending of the rules" can be allowed as well. My Grandfather walked to the synagogue for Sabbath services every Friday night and twice Saturday, until he was in his mid 80's. When his health began to fail, the Rabbi said it would be OK for him to ride to services.
Mark