If this is one of your first attempts at a longer run, you are going to need to prepare your body in advance. You’ve probably already started this by running a few shorter runs, but your food and liquid intake will play a major part as well. You need to maintain proper hydration; staying fully hydrated for a couple of days before a longer run is optimal. If you’re running shorter distances in the days leading up to your longer run, remember to stay hydrated with plenty of water and beverages containing electrolytes. Of course, water is going to be your main source of hydration but you also want to include some electrolytes in your regimen. Our body fluids are mostly water, but our body also relies on nutrients like potassium and calcium, which are obtained from drinks containing electrolytes. Plan to fuel up with electrolytes 2 days before and during your run; water alone will not be enough. You might also want to add to the number of carbohydrates you eat for a couple of days of before your run (not excessively, just a little for added energy). Perfect foods to eat the day of the long run should include nutrients such as sodium, iron, magnesium, potassium, and Vitamins B & C. For example, a small bagel or some toast, fruit, orange juice, and plenty of water in the morning is just one good example, especially if you plan to use a carbohydrate booster right before or during your race. At this point, you are probably aware of the foods that slow you down the most, so simply avoid those foods and maintain hydration.