anal and boyfriend

Ol

my boyfriend loves anal, but I have never been a super big fan of it. like, it doesn't hurt or anything and I am totally fine with doing it when he wants to, but it's definitely not my first choice. tomorrow is out or 1 year anniversary and he wants to try it. however, I don't. I want to tell him, but I know he was looking forward to it so much. before anyone says that he isn't being "respectful" or whatever because I don't want to do it, it's because I haven't really told him. I'm just not quit sure how to tell him i don't feel like it tomorrow since it was already something planned