I'll tell you what my PS said. "Well, I don't know that there is any way to prepare for feeling like you've been hit by a Mack truck."
Just make sure that the index finger that pushes that little button for "MORE MORPHINE" is in working order, and you'll be fine. I suppose you could also practice walking like the hunchback of Notre Dame, and that will give you an idea of how you'll be walking right after the surgery. And be sure that all your friends know for sure WHICH breast it is, so that when they are looking for the "new" breast, they'll know which side to check out.
And while all those things are sad but true, it was also advised that I work on abdominal crunches before the surgery to increase the blood supply to the abs. (I would also recommend working on the oblique crunches, because those are the muscles that are going to have to start helping support your spine.)
Most importantly, remember that this, too, shall pass. You'll be fine. I swear, only a man could have thought up this surgery! I hate to tell you that, my PS nurse, the one who told me that I would be back to my "old self" in 6-8 weeks was hit by this disease two years after I had it. I went in for my 2-year check-up, and she looked terrible. I had no idea she was being treated for BC when I asked her if she was "okay." She told me that she had had the surgery, and she very quietly asked, "when do you start losing that 'tight' feeling?" I just told her that it would get better, but it really does take a while. I guess everyone is different.
Hope your surgery goes well, sweetie. And I really don't say these things to scare, but to prepare. There is nothing worse than to expect to "feel like your old self" in a few weeks, and then not really feeling that way for months. I was functional again in 6-8 weeks (went back to work after 6 weeks, and I have a physically demanding job chasing babies all day), but "normal?" It was more like 6-8 months, if not longer. Getting back to my usual routine was good for me.