Sleep.row machine and peloton. The rowing machine will make your arms a back burn like hell and you will feel the same muscles burning on a big tuna fight. The peloton will strengthen your core, legs, and ass and will also help your stamina. Its rarely the case where some one doesn't have the strength, but more often than not they don't have the endurance. If you can get comfortable rowing and cycling for up to an hour there isn't anything in our waters that can break you.
Another thing to really pay attention to is hydration, sun exposure and sleep. Any one of those out of whack and it wont matter how much you exercise.
That's a biggie for me. I can go without it for awhile, but then I get really cranky puss.
I'll leave that topic for another post