After a day at Disney World, you can safely skip a few gym trips. Mickey's stomping grounds are tons of fun to explore, but a typical day at the park involves lots of walking and more than a little sweating. Staying hydrated keeps you and your kids on your feet and out of the first aid center. Buying water in the parks is a pricey option—and an unnecessary one. Visitors can bring their own water into Disney World.

Disney World is accommodating to guests, especially those traveling with young children, so the parks have few rules regarding bringing drinks inside the gates. You can load a bag entirely full of water bottles without security raising an eyebrow. But don't do that. Pack as lightly as you can for a day at Disney World, because everything you bring, you'll have to lug around a crowded park.

Bring one water bottle per person. Make sure they're full before you leave your hotel room, because it can take an hour or more to get to the park, get through the security and admission lines and actually get through the gates. Once you're inside, refill the bottles from drinking fountains, although Disney's fountain water doesn't taste great. You can also ask for a cup of ice water at counter service restaurants.

Glass containers are not allowed into Disney World, with the exception of baby food jars and other similarly small items. If you try to bring a glass bottle into a park, you'll have to either take it back to your hotel or car, or forfeit it at security. Bring metal or plastic water bottles only.

As long as you don't use glass containers, you can bring any food you want into the Disney World parks. Small coolers are allowed, as long as they're smaller than 24 by 15 by 18 inches. If you need to bring a larger cooler for medications, you can store it at Guest Relations or in a locker.

It's a good idea to bring snacks into the parks, to ward off temper tantrums before they start. Food lines can be long around mealtimes, and if your kids get hungry when you're 30 minutes into the Splash Mountain line, you won't have to duck out to get refreshments. Bring crush-proof snacks like granola bars, trail mix, cheese sticks and dried fruit.

Orlando isn't always blazing hot, and afternoon rain showers are frequent. Mornings and evenings can actually be chilly in the parks, especially between autumn and spring. But it's important to bring water no matter the weather, because the exertion and excitement of a Disney World trip can be dehydrating for kids, and for you. If you need to, set an alarm reminding you to have a water break, or pull out the bottles whenever you're waiting in line.

If the day is really hot, plan to spend the afternoon on cooler attractions. In the Magic Kingdom, try the Carousel of Progress in Tomorrowland and the Hall of Presidents in Liberty Square. Cool off at Ellen's Energy Adventure in Epcot, the Star Wars Launch Bay in Hollywood Studios and the Flights of Wonder show at Animal Kingdom.