It's the near-barefoot aspect that I was concerned about. It feels so good when you first do it that you tend to way, way overdo it.
For the first 3 or 4 months, I walked 2 miles every evening. One day, I ran about 100 yards and almost fell out. Now I can do several miles (even and non-life threatening pace) with no problem. Trust your body. It'll tell you how you're doing.
