“Pain” just means “a feeling I don’t want.”
“Pleasure” just means “a feeling I want.”
That’s all they are.
There’s no pain or pleasure in the feeling itself. A feeling is neutral until I have an opinion about whether I want it or not. It’s the want that makes it pleasure or pain. Without the want, neither pleasure nor pain can exist.
If I’m honestly fine with a feeling continuing, that feeling is not pain. It literally doesn’t “hurt,” no matter what the feeling is or how intense it is.
So if I don’t wish to live in pain, I can work with my opinion about what I’m feeling.
When I am not attached to whether or not I’m having a particular feeling, I am free from suffering.
All feelings live in the body, and are always leaving the body.
And the body is not me.
So nothing really needs to happen in any preferred way in the body. Things are just happening, swirling into and out of this localized eddy of universe I call “me.” They have nothing to do with the true me. And they have no meaning that I don’t arbitrarily assign to them.
If I simply witness a feeling - if I locate it in the body and just notice its “feelingness” - my experience is that it has no qualitative (good / bad) component on its own. I also notice that no feeling ever stays. It is only there as long as I notice, and often not even that long.