I think everyone is right, there is lots of the "good" food available to stick to this, and you are going to feel so proud of yourself if you stick to it. BUT, if you are finding it really hard, maybe promise yourself that you can have a "treat" on the very last day of the cruise if you still want it - chances are that by then, you will have become so used to eating the "good" food on the cruise and so busy with all the activities, you won't even want that treat on the last day.

Good luck, and have a GREAT time!!