If you are having these doubts I would suggest that maybe you should think again and possibly consider a 2 or three sections of a world cruise. The longest we have done was 37 days and for us as well seasoned cruisers that was enough but it really is a personal thing and a decision only you can make. I take it that if you withdrew now you might loose a small deposit or maybe not. One of the drwbacks of a long cruise is that your clothes tend to shrink !!!! hope that helps Nei.
I joined the end of QE2 World cruise in April, there were 3 question asked by us newbies 1 have you enjoyed it? YES 2 Are you looking forward to going home? YES 3 Would you do it again? NO. Maybe it's a once in a lifetime event - do it, relax and enjoy your holiday you are very lucky and I'm very enviou.