My advice would be to exercise as much as possible without overdoing it which can make you quite tired during treatment. For me, HT is the real issue, after a year on it(and another 2 to go😟) my joints are stiff and ache. Regular stretching is a must and if possible regular gym sessions. If you’re not a gym person buy a set of resistance bands…a lot cheaper and I I can do similar exercises to those I do in the gym.
I also find cycling my ebike really good exercise without getting getting exhausted, and it’s really good fun too.
I think exercise is so important that more support should be available.
enjoy your cruise and just make sure your travel insurance are informed about the PCa.