strength and weak
Isaiah Chapter 40:29
He giveth power to the faint; and to them that have no might he increaseth strength.
Isaiah Chapter 40:31
But they that wait upon the LORD shall renew their strength; they shall mount up with wings as eagles; they shall run, and not be weary; and they shall walk, and not faint.
2 Corinthians Chapter 12:10
Therefore I take pleasure in infirmities, in reproaches, in necessities, in persecutions, in distresses for Christ's sake: for when I am weak, then am I strong.