Still it's nice to know I haven't lost ALL cardio condition. And when I get frustrated by these minor setbacks (such as illness), I try to remind myself that fitness is a lifetime commitment, and there are going to be good months and bad months, layoffs and returns.
I'm pretty pleased that despite three cons in a month and an illness-related layoff, I managed to jog three miles just now. I think I could have made the full six, especially at the slow pace I was moving at, but cooler heads prevailed. Running at sunset seems to work pretty well; it's still hot, but the lack of direct sunlight makes all the different. It's just hot, not punishing.