Monday I walked out to Dairy Rd and back. The time was about 20:40, which is close to my personal best (20:36).
Tuesday I did not walk, but had a yoga class that was quite strenuous (as yoga goes), including dripping sweat all over my mat.
Wednesday I had a motivation failure -- I just wanted to sit at my desk and work and not go out and sweat and strain.
Thursday (today) it was Dairy Rd. again (10:40 out, 11:00 in, 21:40 overall). It seems my lower legs are currently the limiting factor. On the return trip I had to shorten my stride to keep up the step rate (or, i suppose, keep the stride long and slow the step rate), because my calves were complaining.