Ordinary people need to drink eight 8-ounce glasses of fluids per day. Marathoners need more than that: a minimum of 80 ounces of fluids (including about 30 ounces of a noncarbonated sports drink) every day — more if you can tolerate it. You absolutely need fluids to push toxins out of your body and rehydrate muscles.

To save money, buy Gatorade powder and mix it up yourself. If you buy the huge cans of powder at price clubs, you can make it about 80 times cheaper than if you buy it already prepared.