Adam Clarke on Proverbs 18:14

The spirit of a man will sustain - A man sustains the ills of his body, and the trials of life, by the strength and energy of his mind. But if the mind be scoundrel, if this be cast down, if slow-consuming care and grief have shot the dagger into the soul, what can then sustain the man? Nothing but the unseen God. Therefore, let the afflicted pray. A man's own spirit has, in general, sufficient fortitude to bear up under the unavoidable trials of life; but when the conscience is wounded by sin, and the soul is dying by iniquity, who can lift him up? God alone; for salvation is of the Lord.