what is the required degree to be a professional writer in the personal development field ?

I want to be a professional writer in the personal development field like jack Canfield and Antony Robbins.
I believe that people will not trust me if I am not holding a certificate or a degree which will make me qualified for writing in the subject .
what is the required degree to be a professional writer in the personal development field ?

Professional writers often hold degrees in language(English) or communications or journalism. For your specific field, you might consider a degree in psychology as well.