I was hoping for an hour, but I was coughing too much to stay on - lungs still just very full of junk, though I am otherwise feeling much better. Will try for an hour tomorrow with a strict zone 2 cap. I will count it a partial success rather than a failure: got some endorphins going and worked up a good sweat, at any rate.
20 mins. elliptical (zone 2/3, avg HR 144, max HR 156)