It seems that our brain waves are able to etch and form pathways or channels across our minds.  Our thought patterns (habits) then begin to shape our mind, will, and emotions.  People who have negative thought patterns are usually prone to worry and fear. 

Whatever is fed into the brain will produce good or bad brain waves (thoughts and patterns).  The brain is the origin of thought and nervous coordination. 

A very nervous person is one whose thoughts have been formed by trauma, harshness, sorrow, and a host of other evils.  A pattern of worry and fear can begin a process of establishing strongholds of insecurity, guilt, anger, and weakness.  The very best plan for renewing the mind is the Word of God and life in the Holy Spirit.

Romans 12:2, "And do not be conformed to this world, but be transformed by the renewing of your mind, that you may know what is that good and acceptable and perfect will of God.