Yes, I seriously thought God couldn’t use me. During every Mass I ask God to come into my heart and allow Him to work through me and yet I never feel adequate enough for it. Seeing this has made me realize priests, monks, and nuns aren’t the only worthy tool of God’s hand.
The Bible verse is 1 Corinthians 1:26-29 –  For see your vocation, brethren, that there are not many wise according to the flesh, not many mighty, not many noble:  But the foolish things of the world hath God chosen, that he may confound the wise; and the weak things of the world hath God chosen, that he may confound the strong.  And the base things of the world, and the things that are contemptible, hath God chosen, and things that are not, that he might bring to nought things that are:  That no flesh should glory in his sight.