"Daily Sixteen"
Some call it "circuit training", some call it "timed sets", it's also referred to as "The Quarterdeck" or "The Daily Sixteen"
Basically it's quickly and smartly done calisthenics...non stop.
Here's an example:
Pushups for 40 seconds,
crunches for 40
pullups (max)
mountain climbers for 40
leg lifts for 40
dips (max)
side straddle hops for 40
flutter kicks for 40
chair squats for 40
body twists for 40
Repeat this 3 more times (4 total sets)
Increase the 40 to 1 minute.
It hits all major muscle groups...and it gets you winded.
If you don't have pull up bar or dip bar...just do any extra couple of sets of exercises...shoot for 25-30 minutes total time.
No rocket science... you can do it on a ship, in a hotel room, anywhere you have a patch of floor space...
Try it out.