Did a 50 min jog today. I felt really stiff and tired for no apparent reason for the first half but at around 30min into it I was really cruising. The pain I had in my ankle disappeared and I got my wind back and ran the last half about 8 mins faster than the first with less effort.
I really don't know why some runs are easy and smooth and others are not so. I guess I'll know more with experience and simply keeping a record on this blog may offer up some answers.