Went on my first cruise this year as well and like you, didn't know what to make of it beforehand. This was an Alaskan cruise. I got used to the lally gagging around and broke into a relaxed mode. If I had to say what kept my sanity was going off the boat. I bought a whoppin 35 mm camera with an array of lenses so I could keep busy. Got a shot of a grizzly 1/4 mile away that looked like you could walk up and touch him. I did not eat anything I could say I didn't like including venison they served. Everyone is super accommodating. I got sick one day as I got into some bad salmon but that was it. As my wife was motion sick the entire trip, we are not going cruising again. On the last day, I found out about the onboard acupuncturist who makes the claim that of all medications and patches, acupuncture is the most effective of mitigating motion sickness.
If I could not get off the boat, I would not go on another one, but hey, I had to experience it for myself.