A Shepherd Looks at Psalm 23, by W. Phillip Keller is the basis for this study. We'll be taking turns leading out so will anticipate you are reading the book. Will make my comments here.
Our Bible study group recently studied the Book of James. We zeroed in on the concept of the tongue and its duplicity with a specific focus on how we talk to ourselves in our heads. . .the goal of course being to speak God's truth via the tongue in our minds.
A very important pre-requisite for successful shifting of the messages we tell ourselves to the positive side of the spectrum is dependence on the One who knit us together in our mother's womb and wants us to know we are His chosen, beloved children.
A Shepherd Looks at Psalm 23 steps back a little from the tongue in our minds and focuses on the Shepherd. If we are to depend on Someone other than ourselves; if we are to fully trust, then we benefit from knowing the One on whom we depend.