Today is Marathon Day in Boston. Thousands of runners from around the world will come to run the 26.2 mile course from Hopkinton to Boston. This is the 116th year of the race, but in all those years I doubt the runners have ever encountered the heat they will today. The temperature is suppose to reach the high 80’s. Even the most seasoned runners have been advised to pace themselves carefully. Upon hearing the warnings, my young daughter asked me what it means to pace yourself.