You stand in your bedroom, take a deep breath and clear your mind to answer a very important question: "What do I wear?" It's kinda chilly, but not really cold, a little breezy but not blustery. You're going to be working really hard, getting the heart rate up, working up a sweat, maybe testing your lung capacity. "Layers," you answer. A base layer that breaths but still keeps you warm when it's wet, a light shell that keeps you warm but compresses into a tiny ball if you get too hot. Some light gloves, a breathable cap..."Yah, yah, yah." And you rifle through your drawers, closet and laundry basket to put together the perfect kit.