Nothing is more fatal in the spiritual life than the thought that we can do anything good without Our Lord, and our self-love is so subtle, that unconsciously we attribute to ourselves the little good that we do, which spoils everything. Our Lord, out of love, leaves us sometimes to our wicked nature, and then we are frightened in seeing all the evil and the possibilities of evil hidden in us. It is not that we are worse than before, but Our Lord lets us see the depths of evil which grace had covered. During these moments, we should act in union with God's designs, by humbling ourselves profoundly and throwing ourselves into God's arms.
The devil tries to trouble you by his subtleties, so that you may cease to act well for fear of acting from vanity. We must never cease doing well for that reason, but quietly purify our intention. The best way is to unite it with Jesus Christ, and with His intentions, and if there is anything imperfect in your intentions this union with Jesus Christ will heal it.
As for what regards the desire for perfection, you ought to seek it with all the ardor of your soul, but at the same time resign yourself to walk at the rate that Our Lord wills for the moment.
--Blessed Columba Marmion