He does not let me catch my breath, but overwhelms me with bitterness.
What Job had said of man's utter inability to contend with God he here applies to himself, and in effect despairs of gaining his favour, which (some think) arises from the hard thoughts he had of God, as one who, having set himself against him, right or wrong, would be too hard for him.
Commenting on Job 9:14-21
If I speak of strength, lo, he is strong,.... Or think of it, or betake myself to that, and propose to carry my point by mere force, as some men do by dint of power and authority they are possessed of; alas!
Job 9:16-20 16 If when I called He really answered, I could not believe that He would hearken to me; 17 He would rather crush me in a tempest, And only multiply my wounds without cause; 18 He would not suffer me to take my breath, But would fill me with bitter things.
Commenting on Job 9:16-20