Thomas a Kempis, The Imitation of Christ 3.51

That we must give ourselves to humble works when we are unequal to those that are lofty 

1. "My Son, you are not always able to continue in very fervent desire after virtues, nor to stand fast in the loftier region of contemplation; but you must of necessity sometimes descend to lower things because of your original corruption, and bear about the burden of corruptible life, though unwillingly and with weariness. So long as you wear a mortal body, you shall feel weariness and heaviness of heart. Therefore you ought to groan often in the flesh because of the burden of the flesh, inasmuch as you cannot give yourself to spiritual studies and divine contemplation unceasingly. 

2. "At such a time it is expedient for you to flee to humble and external works, and to renew yourself with good actions; to wait for My coming and heavenly visitation with sure confidence; to bear your exile and drought of mind with patience, until you be visited by Me again, and be freed from all anxieties. For I will cause you to forget your labors, and altogether to enjoy eternal peace. I will spread open before you the pleasant pastures of the Scriptures, that with enlarged heart you may begin to run in the way of My commandments. And you shall say, 'The sufferings of this present time are not worthy to be compared with the glory which shall be revealed in us.'"

IMAGE: Jean-Francois Millet, The Angelus (c. 1859)