The effect of meditational practice is 'change'. It is not a mere superficial change like the change of dress or wearing a facemask, but it is profound - it is the 'change of heart'.
The change of heart, thus, positively results from the perception of psychic centres. There are a number of centres in our body. The meditational exercise could be in the form of perception of individual centre or in the form of collective perception or cyclic perception. In any case, as soon as our psychic attention is focused on a centre, its activity begins to become balanced and its chemical output is changed.
To use an analogy - what used to be the special agents or spies of the enemy (karma-sarira) change sides and defect to become the agents of the psyche. The change is primal and in the root itself.
Since all the primal urges are endocrine expressions, transmutation of the hormonal synthesis must bring about a fundamental change in the attitudes themselves. Let us consider the history of a chain-smoker who participated in a preksa dhyana sivira (a ten-day residential course). Before coming to the sivira, whenever he was told about the dangerous risks of cigarette-smoking such as lung-cancer, emphysema, etc., he used to argue (illogically of course), "whatever is produced in the world is surely for our pleasure, otherwise why are they produced at all? If all stop smoking, the cigarette factories would have to be closed down and it will be a great national loss", and so on. It is clear from such illogical arguments that any amount of logic would not succeed in convincing him to abstain from smoking. Fortunately, he joined a training sivira, learnt the technique of Preksa Meditation, and made good progress in learning the technique of perception of psychic centres. His hormonal synthesis began getting transmuted. This had a profound effect on his nervous system and mental state. The insistence of the demand of the addiction weakened and was ultimately destroyed. Not only did he stop smoking but got nauseated when others smoked in the vicinity.
This can illustrate change at the root - the change of heart.