2 Corinthians 10:17-18
It doesn't matter what you think of yourself, unless you think a lot of yourself, in which case it matters a great deal because God doesn't buy into boasters.
So what you think of yourself matters a great deal.
If you are puffed up and self-assured, you will be found wilted and left wanting by God at His final judgment.
The ONLY approval that matters is His approval of you.
All the self-esteem in the world will not survive the melting pot of God's pure assessment.