During last cruise I was on, I didn't do even bring my running shoes or use the workout room. If its purely calorie in's and out's you're worried about, you may find that 12 hours a day wandering the ship, climbing stairs and island exploring burns as much or more as an 8 hour day at the office sitting capped by a 7 mile run. I am bringing my running shoes, though, this time in case Im not wore out by morning anyways. In any case, I've alloted myself a few days of yummy stuff the way people save up money, I'm building up fitness beforehand.
Cruisin' to the Bahamas