Ships have improved in so many ways and smooth running is one of the improvements particularly with the larger vessels. If you hit stormy weather the ship may move about a bit but you are going in July when the weather in the Med is at its calmest so don't work yourself up because that will just make things worse. Most people do not suffer sea sickness even those who suffer from car sickness so just relax and look forward to a wonderful holiday. ..... Neil.
Sea sickness is mostly in the mind and in todays large resort ships should never cause you much of a problem. When you are onboard and all seems relatively calm, sit on the upper deck and line up the horizon with the ships guardrail. You will see straight away that the ship is rolling and pitching to some degree but the rest of your senses probably dont even notice it. Relax and enjoy it. Rough weather is a good time to catch up on sleep so you can party more when it all calms down.
I tend to suffer from sea sickness and travel sickness generally, but have now been on several cruises with no problem whatsoever. Before I board the ship the first day, I take 1 travel sickness pill - this covers me for the first day - just in case! By the second day I have my "sea legs" and have never had a problem, even in rough seas. Also the bigger, the ship the less you feel the movement - it's not like a trip on a small boat trip round the bay. I am now a converted cruise fanatic. Go, enjoy your cruise.
Just a point of interest. While I find Stugeron an good remedy - taken BEFORE you feel ill, a recent 'Mythbusters' programme dealt with motion sickness remedies and found that ginger pills were the most effective 'non-drug' remedy. Apparently used by Chinese sailors in days gone by. I haven't tried it myself yet.
I get car sick, air sick, bus sick just about all modes of transport! never been ill on a cruise even when it was really rough seas! Just to put your mind at rest take a packet of ginger nut biscuits and nibble for first few hours on board, and after dinner. Ginger really does work! Also your cabin is perfectly placed to avoid motion sickness. After first night you will definetly be fine!