I often make fun of commercials on TOA (exhibit A) but I do make exceptions (exhibit B). The latter category doubled recently thanks to this Nike running ad; the important part starts after thirty-five seconds, where (SPOILER ALERT) Joan Benoit Samuelson runs in from the right side of the screen, and I learn something about running.
I've read quite a bit about "forward lean", which keeps most of my weight directly above my knees every time my feet hit the ground. This leads to an efficient running motion that manages the long-term stress to my legs, which is a vital concern at this stage of my life; today's subtle adjustments could add years to my running. I've read (and written) enough about this to exhaust any loyal reader; I'm hoping there are many more such sentences in my future. But no matter what I read about "forward lean", I don't think any book can explain it better than those three seconds in the video, when Joan Benoit Samuelson runs in just as she's done for forty years, and shows us how to keep running.