(Watch from 45:26 to 53:14)
The cows (attachment) that are the most difficult to release is your idea. Especially, your idea of happiness. Buddhism is a cow also. If you are not careful, Buddhism becomes a cow and Buddha becomes a cow. And you suffer. It depends on you.
And one day, I discovered Buddhism is made only of non-Buddhist elements. Buddhism is not something that can exist by itself. It's like a flower. And that day was a very happy day. Buddhism is no longer a cow for you to protect and to defend. Because you get insight that flower is made only of non-flower elements. And the Buddhism is made only of non-Buddhist elements.
And you discover also that the Buddha is made only of non-Buddha elements. You are free. And you can release the cow called Buddhism. And you can release the cow called Buddha. And you are free from Buddhism. You are free from Buddha. You feel wonderful. And that is why Thay said that the cows that are the most difficult to release is your idea, your notions. And especially, your notion of happiness. So, if you are free from your notion of happiness, happiness may come right away to you. And other cows, they are easier to release.
So, it's nice to release the cow. The more cows you release, the freer you become and the happier you become as a person.