Okay, managed to finally get back to getting back to running. For those not keeping track, I started back to running 32 days ago (according to my exercise journal). There was something "off" in my ankle, and I tried to run through it for about a 1/4 mile (.4km for those using a logical, organized measurement system). It didn't loosen up, so I walked the rest of my planned 2-mile run. The result was that I've been unable to run (literally, unable to use that ankle in a running motion) until 3 days ago. Got my first run in on Saturday (2 miles, alternating walking and running at my desired pace) and another today (1 mile, relatively slow, hating the hills).
I'm reminded how much worse my breathing capability is (and always has been) than my muscular and cardio capability. I've never managed to get my heart rate anywhere much above 60 or 70% when measuring. I simply get too out of breath to push to that point. For example, at the end of my run to day, I measured my heart rate at 126 bpm, just under 60% of my theoretical "maximum". I was entirely out of breath, and my legs were pretty tired (from being out of breath - I'll have lactic acid again, even from that short run).
It takes me a long time to get my breath/oxygenation built up to where I can comfortably run a couple of miles. As soon as my breath becomes comfortable, my legs' ability to carry me increases immediately (proof that it's an oxygenation issue, rather than muscular weakness). I wonder how much of this is a very mild version of the exercise-induced asthma I used to deal with.
Just felt like sharing that.