Maintaining your fluid intake throughout the day is critical. After running, you'll need to replace fluids you lost through sweating. A few glasses of water can make a big difference. To check your hydration levels, use the "pee test." If your urine is the color of lemonade or lighter, you're properly hydrated. If it's darker, you need more water.
You'll also need to replace electrolytes, which can be found in sports drinks, smart water products, gels, chews or salt tablets. If you prefer real food instead of processed sports nutrition, you can also find electrolytes (such as sodium, potassium, magnesium and calcium) in foods like bananas, avocados, pretzels and coconut water. Be sure to check the label on your sports nutrition products, as many contain far too much sugar to benefit post-workout recovery.