Always be ready

Every Christian should consider the following: 1) that the time of your life passes without stopping, 2) that you cannot turn back time and the past is completely gone, 3) that you cannot control the past and the future but only the present which you live at this very moment, and 4) that you do not know when is the end of your life. 

This is why we should always be ready, every day, every hour, and every moment, through a state of continuous repentance while our spiritual situation should be as such as we would like it to be the hour of our death.

St. Tikhon of Zadonsk

Translated by Dr. Nick Stergiou

 http://www.orthodoxpath.org/saints-and-elders-counsels/always-be-ready/