Unless you happen to be part of a competitive sailing team, you generally don’t hear anyone talk about getting fit to enjoy boating. Yes, we’re talking about your personal strength and fitness, not how fit the boat is to move from A to B without actually sinking.
Now obviously certain types of boating are going to require a lot more strength and a much higher level of fitness than others. Sailing generally is going to require some muscle strength. Blasting away in a dragon boat will make every ounce of muscle in your body burn! Whereas sitting back in a motorboat is not even going to get you out of breath. Although I would still argue that being in at least moderate shape is beneficial to pretty much any outdoor activity. After all, if you’re the captain you are in charge of everyone elses safety on your boat, and depending on how fancy that motorboat is you still have to deal with anchoring, and throwing lines out to dock.
Basic cardio fitness is good for everyone and everything. So keep your weight your down, and choose to walk whenever you can. That’s all it takes. Other than that, core strength is probably of most importance to boaters. This includes all those muscles down the center of your body that support pretty much everything else you do – everything from balance to pulling, pushing and lifting. Seriously good exercises for tightening up those core areas are planks – these are far better in my opinion than the old fashioned sit-ups and much easier to do properly without hurting yourself. Lunges are also good, as are kettle bell swings (you don’t have to use a kettle bell, you can improvise here).
You get fitter just by doing an activity anyway, but it can pay to improve those levels before you begin or at any time. Better levels of fitness can certainly make your boating life more fun and allow you to take on greater challenges.