“For as he thinketh in his heart, so is he…” Proverbs 23:7
The word “thinketh” in Hebrew is saar, which means to reason out and “Heart” in the KJV Strongs translates as soul.
So, as a person reasons out in his soul (will, mind and emotions), that is who he becomes.
If you think you are a failure and will never be good enough, you will be.
It’s crucial that our self-perception aligns with God’s word. What we think about ourselves matters.