We must not count on ourselves
If we knew at what time we were to depart from this world, we would be able to select a season for pleasure and another for repentance. But God, who has promised pardon to every repentant sinner, has not promised us tomorrow. Therefore we must always dread the final day, which we can never foresee. This very day is a day of truce, a day for conversion. And yet we refuse to cry over the evil we have done! Not only do we not weep for the sins we have committed, we even add to them…. If we are, in fact, now occupied in good deeds, we should not attribute the strength with which we are doing them to ourselves. We must not count on ourselves, because even if we know what kind of person we are today, we do not know what we will be tomorrow. Nobody must rejoice in the security of their own good deeds. As long as we are still experiencing the uncertainties of this life, we do not know what end may follow…we must not trust in our own virtues.
St. Gregory the Great