But no, the fasting periods were merely times when I wasn't eating, and that includes pushing them out to 30+ hours and going a day without eating and without much hunger on a couple of occasions.

Occasionally, I've had experiences where running was light and energeising and fun, during that intermittent fasting time. I suspect now that the people who say they can't live without exercise and "exercise should be a celebration of what you can do" feel this the majority of the time. In the past, almost always a drag to push through.