On the Remembrance of Death:

Our mind is so darkened by the fall that unless we force ourselves to remember death we can completely forget about it. When we forget about death, then we begin to live on earth as if we were immortal, and we sacrifice all our activity to the world without concerning ourselves in the least either about the fearful transition to eternity or about our fate in eternity. Then we boldly and peremptorily override the commandments of Christ; then we commit all the vilest sins; then we abandon not only unceasing prayer but even the prayers appointed for definite times - we beginn to scorn this essential and indispensable occupation as if it were an activity of little importance and little needed. Forgetful of physical death, we die a spiritual death.

Bishop Ignatius (Brianchaninov), The Arena, Chapter 28, pg 90