The bad news is that two Royal Caribbean ships in the last few weeks have had huge problems with Norovirus (stomach flu). The good news could be that by the time you go they will have tightened up their hand cleaning proceedures. One thing to always do is to wash your hands frequently and do not touch your mouth or eyes.
You will have a great time and do not worry about being bored - unless you want to. There are many things to do on most ships from cooking demonstrations to art auctions (with free champagne) to first run movies. One thing they do not mention is that you have to pay extra for any tours you want to take and unless you have a special deal alcoholic drinks are extra also. Many ships these days just charge a little extra and give free drinks but if not they can be expensive ( like $9 each). Most people go on a cruise to relax .