Brother, do not lose confidence in progressing to spiritual things. While there is still time, while the hour is not past, why procrastinate on your purpose? Get up. Start right now. Say it: “Now is the time for action, now is the time to fight, now is the moment for movement.” When you're going through a bad time, when you're struggling, that's the time to earn your progress. You will pass through fire and water before you rest and refresh. It will take vigor to overcome vice. So long as we carry our frail human body, being without sin is impossible, and neither can we be without weariness and trouble. Gladly we would rest from all misery; but because through sin we have lost innocence, we have also lost true happiness. So we must be patient, looking to God for mercy until this iniquity has passed away, and death has been cut off from life.
O how great is human frailty, which is always vulnerable to vice! Today you confess your sins, and tomorrow you commit the same sins again. Now you propose caution, and an hour later it's as if you had never proposed it. We have earned humility, even if we have not learned humility, since we are so fragile and unstable. And we can quickly lose our spiritual gains by negligence, which we worked so hard to attain with the help of God's grace.
What will happen to us in the end, if so early we become lukewarm? Woe to us if we choose to rest, as if there were already peace and security, while there has not yet appeared one single sign of true holiness in us. It would be better to train like beginners, to gain better habits, so there might be hope of future improvement and greater spiritual progress.
Imitation of Christ by Thomas A Kempis, 1.22 (second part).
Translation focused on contemporary English and preservation of rhetorical force and art