I'm going to be running a marathon in about a week. There's a lot of things they don't tell you when you train for a marathon. For one, they don't tell you how after about 18, 20 miles how your knees and hips start hurting when they've never hurt before. They don't go into detail about the burning you feel in your legs and shins after your long runs. They especially don't tell you about things like chafed areas of skin which—you'll have to trust me on this one—are not for the faint of heart.