For something to die it must live. You must define what is living and then you can define its death process. If your question pertains to a person as a simple organic being we die when our body and its vital organs cease to function, be it by an outside force or by degradation (age). This applies to all organic beings such as plants, insects and animals. If your question delves in the soul as the essence of the human being, then you can explore the different deaths a soul can go through: hopelessness and the lack of purpose in existence steals the soul's energy; injustices born in solitude also kill the soul; anger without focus destroys the soul and those it touches.
When I read about people maintaining peace in the midst of pain, persecution and intense pain it raises an alarm that points to "how do they do that?" I found that God does exist because in the lives of many who've followed Him they've demonstrated life after life by tolerating pain in peace. The soul is eternal. It's its very nature to live forever. It should not live forever alone.