In SN 22.100 below, we find the Buddha teaching that associating anything with the self, causes it to become an object of clinging, and therefore, become a part of the clinging aggregates.
For e.g. you objectify the idea that vaccination is good, after watching a lot of YouTube videos about it or reading articles about it. You think it is "my" policy, belief, faith that vaccination is good and "I" know reasons why it is good. "I" am a pro-vaxxer. It's a belief you hold on to.
Then some anti-vaxxer comes and criticizes or undermines your belief, and this causes you mental grief and makes you annoyed. Why? It's because you clung to a belief and associated with yourself, made it "mine", and when someone criticizes it, you feel that he criticizes you, and this makes you annoyed.
Or if somebody praises your beliefs, that makes you happy. It gives you pleasant feelings.
Things which we cling to and associate with our self are causes for arising of the three poisons of passion, aversion and delusion. According to AN 4.200, you can get affection from affection, affection from aversion, aversion from affection and aversion from aversion.
From SN 22.100:
There the Blessed One said: "Monks, from an inconstruable beginning
comes transmigration. A beginning point is not evident, although
beings hindered by ignorance and fettered by craving are
transmigrating & wandering on.
"It's just as when a dog is tied by a leash to a post or stake: If it
walks, it walks right around that post or stake. If it stands, it
stands right next to that post or stake. If it sits, it sits right
next to that post or stake. If it lies down, it lies down right next
to that post or stake.
"In the same way, an uninstructed run-of-the-mill person regards form
as: 'This is mine, this is my self, this is what I am.' He regards
feeling... perception... fabrications... consciousness as: 'This is
mine, this is my self, this is what I am.' If he walks, he walks right
around these five clinging-aggregates. If he stands, he stands right
next to these five clinging-aggregates. If he sits, he sits right next
to these five clinging-aggregates. If he lies down, he lies down right
next to these five clinging-aggregates. Thus one should reflect on
one's mind with every moment: 'For a long time has this mind been
defiled by passion, aversion, & delusion.' From the defilement of the
mind are beings defiled. From the purification of the mind are beings