Why do mild vs strict Metta guides affect my undisciplined thoughts differently?

My thoughts lack discipline and are in a continual struggle with teaching. I have to decide whether to use a soft and mild guide and one that is very strict and commanding. Would a harsh voice be more effective at putting my mind in check, or would it make my mind more resistant and over thinking? My name is Isha, DOB 8th August 1992. Time: 2:25 PM. Location: Ahmedabad.