If you are prone to motion sickness, do NOT go with a positive attitude and no drugs!
I read over and over 'you can't feel the boat moving.' Well, you can. And, if you are sensitive to motion, you really can.
I did not take meds before I got on the ship and that was a mistake. We hit BAD seas that night and I was dreadfully sick from 6 pm til after midnight. (Yes, I missed dinner, the show, everything.)
That night I put 'the patch' on that night and took the sea sickness pills that
DCL gives out every 12 hours for the remainder of the cruise. I was able to enjoy the rest of the cruise by the next day but even with the patch and the pills, I never felt quite right.
I DO want to cruise again, but I would definitely put the patch on before I ever got on the ship among other things.
(FYI: I did have blurred vision for a few days from the patch. It was a little disconcerting, but things returned to normal after 2 days of removing the patch.)