Gregory the Dialogist

For my sighing cometh before I eat. For the soul's 'eating' is its being fed with the contemplations of the light above, and thus it sighs before it eats, in that it first travails with the groanings of sorrow, and afterwards is replenished with the cheer of contemplation. For except it sigh, it eats not, in that he that refuses to humble himself, in this exile we are in, by the groanings of heavenly desires, never tastes the delights of the eternal inheritance. …

Morals on the Book of Job, Book V ↗

Thomas Aquinas

After he shows that the life of man is difficult because of the unhappiness and bitterness of men, he applies to himself what he said about men in general. In this he expresses his own bitterness when he says, "Before I eat, I sigh," for as laughter is a sign of joy, so sighing is a sign of bitterness of soul. In this he shows the manner of his bitterness from the manner of his sighing. He began his sighing easily, "Before I eat, I sigh." And his sighing was continuous and great. …

Commentary on Job ↗