A few weeks ago I read a very interesting book, "The Biology of Belief" by
Bruce Lipton PhD(a cell biologist)

The topic of this book explains why sometimes affirmations, plans and
success techs don't work and actually how to make them work.

Dr. Lipton recommends another book "Psych-K" written by another author. This books provides techs to find out what beliefs are stored in the subconscious mind and how to change them if it is desired.

Cheers,