Instructions

• Step 1: Weigh yourself Weigh yourself naked as you're getting dressed to run.
• TIP: Before you take a step, chug a tall glass of water.
• Step 2: Fill your bottle Fill up a water bottle with water for runs shorter than an hour. If going longer, fill it with a sports drink.
• Step 3: Pack your bottle Either hold the bottle in your hand, or carry it in a pack around your waist.
• Step 4: Hydrate Drink about 20 ounces of fluids ever hour. The hotter it is the more you'll need to drink.
• TIP: If it's scorching and you know you'll need more than 20 ounces of fluids every hour, carry two water bottles, one filled with a sports drink.
• Step 5: Weight yourself again When you return home, strip off your clothes, dry yourself completely, and weigh yourself again.
• Step 6: Assess your hydration If you've lost weight, you need to drink more during your workout. For every pound less, drink 16 more ounces next time you run.
• FACT: Hyponatremia, or over-hydration, is considered a bigger threat to marathon runners than dehydration.

You Will Need

• A bathroom scale
• A water bottle
• And a sports drink
• A water bottle pack that cinches around the waist