So I checked out a DVD from the library on Chirunning. Despite it's new-agey type name, it about your form, not your spirit. Landing with a mid-sole foot fall rather than a heel strike, arms at a 90 degree angle, relaxed leg muscles, toes pointing straight ahead, etc.
One major component is posture. I've been a slumper since childhood, so this is a challenge for me. In the DVD, they showed this guy putting one palm on his belly, the other on his chest, then sticking up his index finger and resting his chin on the tip. Everything is supposed to line up. Sure. Fine. I can do that. But the DVD emphasized that you should be able to look down and see your shoelaces. I can't unless I lean way back.
So I was standing outside, having finished my run, and eyeing my posture in our big dining room window, which was acting like a mirror. I looked like I was standing straight, but I still couldn't see my damn laces. And then it hit me. "Boobs! It's because I have boobs!" I said loudly, mashing them to my chest with my palms.
At which point I realized a man was walking his dog past our house and giving me a really strange look. I have no idea what he was thinking.