This is found in Proverbs 28:26, and was the point of a post by Pastor Erik Raymond entitled Do You Trust Yourself Too Much?
No matter how well we do in the day to day tasks, if our minds are our ultimate governors then we are nothing more than fools. But, if we are being governed by Lady Wisdom, and in fact, wisdom incarnate (Col. 2.3), the Lord Jesus Christ, then we are walking in wisdom.
No doubt you can sense the same burden from Paul in the New Testament (Rom. 12.1-2) as Solomon in the Old that believers would be bathing their minds in the Scriptures so as to transform hearts and minds by and through the Word. Do you share this burden and priority?
It reminds me of another proverb– the heart is deceitful above all things and desperately wicked, who can know it?