Spanking is pleasant. I do not get turned on by my partner causing me pain or distress though. I just think it's fun for him to slap my ass. And so does he, but neither of us actually want to hurt each other. He wouldn't hurt me if I asked him too. He wouldn't be able to do something hurtful to me. We've discussed it, and thankfully, I don't want him to or I'd be in some trouble. Lol.

Whipping, spanking, grabbing -- fine by me. I like a little roughness, but I do not like force or showing hostility, even if it's "play pretend."

And getting used to it is not my idea of something that should ever be involved in sex. You should never have to "get used" to anything. With sex, you either like it or you don't. There shouldn't be no "getting used to its." Not in my opinion. I don't think you ever get used to certain sexual acts. I think you either like it or you don't. That is just me.

"Screw the Roses. . . " has a really interesting section on this that helped me articulate how I am with "pain".
I'm into what the authors refer to as "total conversion" where there's never really any registering of "actual pain" because the level is kept to where it matches how aroused the person taking it is. (I'm sure I'm not explaining it as well as the book - the whole section is worth reading)

The way it works for me is that activities build in intensity as I get more and more of an endorphin rush. So, as I get "warmed up" I can be hit harder, but it's gradual so I keep feeling good.

In other words, what might hurt at the beginning feels good later on.