Any experience you should be equanimously and objectively aware of perceiving (desirable, undesirable, neither) and sensation (pleasant, unpleasant and neutral) of the arising and passing or the sensation devoid of any craving or clinging while keeping though proliferation in check.
When you let go there is a feeling of renunciation with again is 3 types according to Sal-āyatana Vibhanga Sutta. A house holder seeks sensual pleasure and is temporarily satisfied or unsatisfied by the experience by perceiving and desirable or undesirable or neither. When you renounce householders life you strive to stop this perceiving by understanding the universal characteristics of the experience (changing, unsatisfactory, non self). In this letting go there is a pleasure also whis is non sesual nature. See: Sal-āyatana Vibhanga Sutta, Pañcak’aṇga Sutta, Bahu,vedaniya Sutta
There are 18 mental examination:
(1) On seeing a form with the eye,
one explores a form that gives rise to pleasure,
one explores a form that gives rise to pain [displeasure],
one explores a form that gives rise to equanimity.
(2) On hearing a sound with the ear,
one explores a sound that gives rise to pleasure,
one explores a sound that gives rise to pain [displeasure],
one explores a sound that gives rise to equanimity.
(3) On smelling a smell with the nose,
one explores a smell that gives rise to pleasure,
one explores a smell that gives rise to pain [displeasure],
one explores a smell that gives rise to equanimity.
(4) On tasting a taste with the tongue,
one explores a taste that gives rise to pleasure,
one explores a taste that gives rise to pain [displeasure],
one explores a taste that gives rise to equanimity.
(5) On feeling a touch with the body,
one explores a touch that gives rise to pleasure,
one explores a touch that gives rise to pain [displeasure],
one explores a touch that gives rise to equanimity.
(6) On cognizing a mind-object with the mind,
one explores a mind-object that gives rise to pleasure,
one explores a mind-object that gives rise to pain [displeasure],
one explores a mind-object that gives rise to equanimity.
Thus there are six mental explorations with regards to pleasure; six mental explorations with regards to pain [displeasure]; six mental explorations with regards to equanimity.
‘The 18 kinds of mental explorations should be understood,’ thus it is said in this connection.
See: Sal-āyatana Vibhanga Sutta, Titth’ayatana Sutta, Dhātu Vibhaṅga Sutta, Indriya Bhāvanā Sutta
Where you have to examine the sensations hence you doing it right. This plays a role in removing the roots. See: Pahāna Sutta, Avijja Pahana Sutta 2
