The plot thickens...
As I reflect more on it, I realize I need to widen the view. In those earlier posts, I was simply looking at the tiptoeing that I did that last time, the push that got me through. But in actuality, I had been tiptoeing up to it, then falling back, for at least two years leading up to that. Two years, waiting for some magical moment.
There was nothing special about the moment I quit until I actually quit.