Ahoy, fellow Ample-Americans! Bikini season's pretty much here. Chances are, you're more than a little nervous about shedding those layers, right? Don't be, because there's a cure – one that's way more fun than going to your local gym to huff disinfectant fumes. Go on a cruise.

Sound crazy? I thought so too, until I tried it, many sailings ago. The ship had recently upgraded its fitness center. It seemed a whole lot nicer than the one I joined but never went to back home. (Twist: It was.) I began working out, every single day. As happens, my appetite began to change, too. I put down the rubbery prime rib and the passable cheesecake and started nibbling on salad and other healthy things that aren't quite so terrible as salad. I went home happy, well-rested and a few pounds lighter.

I'd say you'll never believe what happened next, but you probably would. I gained it back. From that point forward, however, I've seen cruises as a great way to get my fitness regimen back on track, leaving me feeling better than when I boarded. How to do it? Read on.

If you always thought you'd work out more if you had a real fitness center just a few feet from your bed, well, you do now. Cruise lines have made giant investments in fitness facilities, many offering panoramic ocean views and more extensive selections of equipment than you might be used to back home. Best of all, they're often nearly empty once cocktail hour begins, not to mention while in port. (If you're wondering who has the best gyms, the answer is Royal Caribbean, particularly their newest ships.)

If you've been on the fence about getting a trainer, now's the time to try. The enthusiastic Aussie (or similar) trainer is almost a cliché on cruise ships now – rates are generally fair and, more importantly, you've got the time. On ships with the Canyon Ranch @ Sea branded facilities – Celebrity is the biggie, but they're on Cunard's Queen Mary 2 as well as Oceania and Regent Seven Seas ships – they'll do a proper fitness consultation that'll help you maximize your time while onboard.

You finally have the time to take that spin class you've been thinking about. Unfamiliar with the world of spin, yoga, Pilates, Yogalates? You've got no place else to be – sign up for a few classes, generally offered for less than the cost of the cover charge at that just-okay steak restaurant a deck or two away. The instructors may not be the greatest in the world, but who knows – you may just develop a passion for spinning that might just blossom into a (healthy) obsession once you get back on land.

Make sure your ship has a proper exercise track. Most ships have them, but some do it better, putting you high up in the sky and away from the pool crowd, giving you a surprising amount of space in which to move around. There's nothing quite like putting in a few miles at night under the stars, or early in the morning before the hangover gang crawls out of bed – you might be amazed at how often you'll have it to yourself.

Hate walking and not so hot on the gym, either? There are other ways to get the old heart rate up. It's truly amazing what some of the lines are squeezing on deck these days – Royal's newer ships are packed with an insane number of diversions – take surfing lessons, go ice skating, climb a wall – you can even do a few laps around the roller rink on Quantum of the Seas. Also take a look at Norwegian's new Breakaway Class, offering a three-story outdoor ropes course that'll put you through the paces and then some.

Choose an itinerary with plenty of sea days. If you're really serious about getting fit, choose a repositioning cruise, or a regularly scheduled transatlantic sailing. On the Queen Mary 2, the exercise track is located on a lower deck and is largely covered, allowing for miles and miles of walking on those long days out in some of the best air you will ever breathe.

On as many nights as possible, skip the main dining room and head for the buffet. This is where you'll have to exercise the most discipline, but for me, the buffet is actually one of the things that make staying healthy so simple – all I need to make it work is a little willpower. 

Being able to pick and choose what I eat at every meal is invaluable. Some say you should actually eat all of your meals in the main dining room, where someone does the portion control for you. I disagree – the "healthy" options there are often far too boring to keep me from the good stuff, packed with salt, fat, sugar and/or carbs. Breakfast is more of a toss-up. Here, the dining room can actually be your friend, as long as you resist the urge to wolf down everything on the pastry tray they keep pushing at you, as happened on my last Seabourn cruise. (Best donuts at sea, and I should know – I ate enough of them.)

They give you free room service. Put it to good use. It's available all day, every day, included in your rate. Hungry between meals? Order a salad, a fruit plate, or something similarly not bad for you. As at the buffet, some willpower is required,  but this can be a decent source of food that isn't going to make you fat (or fatter).

Choose a line that places an emphasis on healthy eating and living. Among the big guys, Celebrity seems to do that best, with their Canyon Ranch-branded SpaClubs, featuring serious classes and activities that are perfect for someone trying to get their health on track. Their Millennium-class ships feature the AquaSpa Café, where you can wake up every morning to smoothies and granola and other healthy breakfast items. They serve lunch as well, meaning you can avoid temptation for at least two meals, every single day you're on board.

It may seem simple, but take the stairs. On many ships, we're talking a dozen or more flights at your disposal, generally wide enough to let people pass so you're not constantly fighting traffic. An early morning run up and down (repeat until you fall over) can be a huge boost to your fitness regimen.

If you have a hard time dragging yourself to exercise on purpose, think big. With more and more megaships afloat, it's now possible to put in your daily 10,000 steps without even setting extra time aside. Depending the line and class, you could almost knock that off in a walk from your stateroom to the buffet. While small ships can be terrific, they often have small, crowded fitness facilities and little more than glorified plunge pools, not to mention limited walking opportunities – even the most dedicated fitness buff will start to feel as if they're going in circles after a day or two.

Skip the bus tours and walk. If you're keen to sightsee, at least choose an itinerary that gives you the most autonomy in each port. It helps to research a little and see where you'll be docking, how easy it is to get out and back on your own two feet, not to mention how safe it is to do so on your own. 

Cruises to European cities, along the Pacific Coast and up to Alaska and New England/Canada are packed with walkable stops – your visits to Barcelona, Victoria, Santa Barbara or Boston can easily turn into all-day walking adventures, all without spending an additional penny on transportation or land tours.

Stress and lack of sleep are the enemy of weight loss. Luckily, you'll (hopefully) experience neither on most cruises. If you're at all the cruising type, you'll find yourself sleeping better and relaxing very quickly – two important steps toward improving your health.

David Landsel is a contributing writer for the low-airfare listing site Airfarewatchdog.com. Follow him on Twitter @davidlandsel.