What have you learned, so far, about this barefoot/natural running thing?

I'm glad you asked.  I have officially been at this for 6 weeks now.  This seems like enough time for me to be able to share some of my thoughts on what I have learned so far.  Fair warning, after only 6 weeks, I really know nothing for certain.  Not even whether this little experiment will be successful.

Progression - After 6 weeks I am up to a whole, whopping 1.75 miles at a time.  Doesn't sound like much, huh?  I have a very strong suspicion that my glacial pace of progression has kept me from developing any type of injury, such as an Achilles' tendonits/rupture, stress fracture or plantar fascitis.  This is one thing it seems I am doing right.

Sensitivity - As previously mentioned, I have long considered myself a "tenderfoot", not tolerating much direct tactile sensation on the soles of my feet.  It is safe to say that this is also improving.  I spend as much time as I can barefoot.  There has also been a decent development of callus on the sole of the feet.  All of this has helped with the "tenderfoot issue".  On the flip side, I am nowhere near being able to walk on any and all surfaces while barefoot.  There is still a lot of heat sensitivity (thanks hottest summer on record!) and even things like walking on wood chips is not yet comfortable.

Running Form - There is a lot to say about this (it's also a lot to think about all at once).  Most sources have been consistent about what good, natural running form looks like.  Let's break it down.

• Foot Strike - all sources advocate landing on the forefoot or the midfoot (essentially a foot flat landing).  Adapting to this has been relatively easy. Who would want to heel strike without a shoe on?  Highly uncomfortable.
• Does the heel ever make contact?  Yes, but only after the forefoot has made contact and then, only lightly.  I still have to focus on letting this happen, although it is becoming more "automatic".  I find that if I don't let the heel lightly come down, it puts too much strain on the calf muscle.
• Foot strike under the body - does my foot strike happen under my body or in front?  I don't know.  I can't bend my neck quite that far.  Seems like it, though.
• Posture - all my sources advocate a very upright, eyes focused ahead posture.  Looking down is not an option.  This has been a struggle.  I have long been in a bad habit of looking down while walking and that carries over to running.  Typically, I pick a distant object and try to focus on it.  Looking forward makes sense.  It allows you to see upcoming obstacles and is better for respiratory function (I've heard breathing is important for aerobic activities).
• Trunk Lean - While maintaining the upright posture, you still need to leanthe trunk forward from the shoulders.  It wasn't until my Day 40 run where I really "got" this (just a little bit of "got", though).  When I was able get that little lean forward, it gave me the sensation of falling forward vs running forward.  I could understand what others mean when they say that your running stride naturally flows from the forward lean.
• Heel Kick - in all the videos and photos of good natural runners, the thing that stands out to me is the heel kick.  Take a look at a long-legged, African distance runner and it will look like they are going to kick themselves in the butt with each stride.  I kinda wish I had some video of myself running so I could see if this is going on.  Trying to assess your own heel kick is kind of like trying to look at your own back.  We're just not built to do that.
• Cadence - 180 steps per minute is what everyone advises.  Oddly enough, I have a digital metronome so I can check what my cadence is.  Unfortunately, I haven't used it for weeks.  I really should bring this along on my next track run.  That might be the last little variable I need to "get".
• Easy, light and fast - In the book Born to Run, Caballo Blanco sums up the Tarahumara running style as "easy, light and fast" where you need to learn to run easy first, then light, and fast naturally flows from the first two.  I have a feeling I am getting close to easy, but what exactly defines easy?  I haven't quite put my finger on it.   Light?  When I have focucsed on "light", it seems like I start bouncing or springing too much, which seems like wasted energy.  The concept of light will have to jostle around my cranium for a while before I understand it.  Fast?  Nope, not yet.
• Theoretically, if I can put all of the above together, I should be set to go and be able to run with much less likelihood of an injury.  I guess we will have to see.

Fun - yes, I am having fun and fun feels good.  If I can keep on progressing like I have and get up to 30 minutes while still remaining comfortable, in the musculoskeletal sense, I will consider this experiment a success.  At that point, it will really be fun and if it ain't fun, what's the point?