In all things consider the end; how you shall stand before the strict Judge from Whom nothing is hidden and Who will pronounce judgment in all justice, accepting neither bribes nor excuses. And you, miserable and wretched sinner, who fear even the countenance of an angry man, what answer will you make to the God Who knows all your sins? Why do you not provide for yourself against the day of judgment when no man can be excused or defended by another because each will have enough to do to answer for himself? In this life your work is profitable, your tears acceptable, your sighs audible, your sorrow satisfying and purifying.
The patient man goes through a great and salutary purgatory when he grieves more over the malice of one who harms him than for his own injury; when he prays readily for his enemies and forgives offences from his heart; when he does not hesitate to ask pardon of others; when he is more easily moved to pity than to anger; when he does frequent violence to himself and tries to bring the body into complete subjection to the spirit.
It is better to atone for sin now and to cut away vices than to keep them for purgation in the hereafter. In truth, we deceive ourselves by our ill-advised love of the flesh. What will that fire feed upon but our sins? The more we spare ourselves now and the more we satisfy the flesh, the harder will the reckoning be and the more we keep for the burning.
– From: Thomas a Kempis; The Imitation of Christ