Hydration is essential when you are exercising. How much water you need and when you need it really depends on the length of your walk and the intensity of the walking. A casual stroll while chatting with a friend is a very different half hour spent than one of fast, high intensity walking. The general rule of thumb, however, is a woman of average weight needs 4-6 oz. of water for every 15 minutes of exercise. If you plan to exercise for longer than 90 minutes, you may want to consider using a sports drink after your workout to replenish your body with the nutrients and electrolytes it needs. Just remember, sports drinks are full of sugar and are unnecessary calories for regular workouts. I suggest them for those “in training,” when doing long workouts preparing for an event. For example, I have my kids drink them after a 2 hour hockey game or dance practices. If carrying a water bottle as you exercise is problematic for you, try these different options: There are now waist packs that hold a water bottle, as well as your car keys and/or a cell phone. This will free up your hands while you are walking. I like to freeze my water bottle for hot days and as it melts it stays cold for a longer period of time—not to mention the bottle keeps my lower back cool. Try out the Camelbak Hydration System. You can find them at most sports stores or at many sport-related websites. I love this option because it offers a constant stream of water as you are exercising. It is very easy to carry on your back and doesn’t bounce around as you are moving. This is a great option for longer walks and my family even uses them while we are skiing or on long bike rides. Set up your walks and runs on paths where you know there are drinking fountains nearby. Or take some time to research where some drinking fountains are on your current walking course. Often public trails and parks are set up with us walkers and runners in mind and they have drinking fountains—you just have to find them! More from Prevention: 4 Tricks To Stay Hydrated