Just as drugs or medicines are useless to those who are free from physical or mental illness, positive thinking is irrelevant to the mind that is free from ignorance and egoism.
Positive thinking is one of the yoga practice to counter negative thinking, but it’s not the goal of the yoga practice, as if the mind needs to be thinking in the positive way, to be positive and stay positive, it means that the mind is still not free from being determined by the mind perception of duality under the influence of ignorance.
The mind that is free, perceives all the names and forms as they are, or sees things as they are. Everything is just what it is, neither good nor bad, neither positive nor negative. This mind doesn’t need to think positively. It doesn’t need to practice positive thinking to counter negative thinking as there is no negative thinking. All forms of yoga practice exist as different tools for the ignorant egoistic mind to be free from ignorance and egoism. Any form of yoga practice is useless to the mind that is free from ignorance.
The mind is not free, is due to it is still perceiving all the names and forms under the influence of ignorance and egoism perceiving duality of good and bad, positive and negative, and the mind is being determined by duality, where there’s craving/clinging towards the mind perception of the quality of good and positive, and aversion towards the mind perception of the quality of bad and negative, then this mind can practice positive thinking to counter so called negative thinking, or more precisely, ignorant egoistic thinking in the mind.
It’s like drugs or medicines to counter certain physical or mental illness, positive thinking is just a tool to counter negative/ignorant thinking. It’s not freedom if one needs to depend on drugs or medicines all the time, similarly it’s not freedom if the mind needs to rely on positive thinking as the mind is still not free from the influence of ignorance and egoism.