To thank our incredible fans for their support of our cookbook project, we're giving you a sneak peak of a favorite recipe from Run Fast Eat Slow. We never expected to receive over 650 inspiring stories from each of you in response to our search for runners willing to help us with recipe testing. Thanks for your enthusiasm! Happy baking. XO, Shalane & Elyse Superhero Muffins Yield: 12 These muffins were designed for superheroes like you. They're packed full of veggies, and are sweetened with…