This is the way that my thinking has been going over the past few days:
If you want to change the way that you've been running for 35 years, then it's gonna take a few months or even a couple of years to do it.
As Keith says in the book, and in his recent reply to my last post, you'll do it quicker without shoes on. But quicker is a relative term, and I think this still means months.
Logically, I'm guessing that running properly (out of cushioned shoes) is going to be using muscles that you've never used before. And how long did it take to build up some of the muscles you do use today? Up to 7 or 8 years, that's how long. (look at photos from today and from 2, 4, 6, 8 years ago, and you will see muscles now, that didn't exist then) (I took up 800m running 8 years ago)
And I'm guessing that most of those muscles are in the feet.
So this requires real patience. Approach it almost as if it was a new sport. Say you were taking up white water kayaking from nowhere. You'd give yourself at least 2 years to be mildly competent, and that's assuming you can get out on the water 3 or 4 times a week.
Well, I think some of those small muscles are going to want time and space to grow, recover, grow, recover, grow, recover.
I guess Keith and Heidi need to balance the honest truth with the prospect of putting people off for ever. Tell the average weekend road racer that they need to have at least 6 months off racing and they'd baulk at the thought.
But I'm serious about this. After 8 weeks I know how good this style of running feels, how fluid and how light on my feet I feel. But I know if I was to hit a 60 or 70 mile week this month (which I would usually do at this time of year) then that would probably injure me right now. I'll aim for that volume in January, I think.