Isaiah 40:28-31
28Do you not know? Have you not heard? The LORD is the everlasting God, the Creator of the ends of the earth. He will not grow tired or weary; His understanding is beyond searching out. 29He gives power to the faint and increases the strength of the weak. 30Even youths grow tired and weary, and young men stumble and fall. 31But those who wait upon the LORD will renew their strength; they will mount up with wings like eagles; they will run and not grow weary, they will walk and not faint.