The mind itself is a potent instrument for change, the only one there is.
All change must take place in the mind first,
for all action is a result of thought and the resultant impulse or motivation.
Your understanding is always based on the thought system to which you adhere. You never learn on your own just as no decisions are made in isolation.
You learn and you decide with the help of one of two possible teachers: the Holy Spirit or the ego. There are no others.