John Owen on faintheartedness (Hebrews 12:3)

Consider him who endured from such hostility against himself, so that you may not grow weary or fainthearted (Hebrews 12:3).

John Owen writes in his commentary on Hebrews 12:3d about being fainthearted or losing heart.

Literally, “faint.” This fainting consists in a remission of the due acting of faith by all graces and in all duties. It is faith that stirs up and engages spiritual courage, resolution, patience, perseverance, prayer, all preserving graces and duties. If it fails here and we are left to fight our difficulties in our own natural strength, we will quickly grow weary. This is where all spiritual decline starts, namely, in not exercising faith in all these graces and duties.