Legs Feeling A Bit Feeble

So I ran one of the new Zwift training sessions yesterday and it was pretty good. Cooled down afterwards with twenty minutes on the bike. Today I was planning on doing an hours group ride followed by a run. I did the ride but as the hour progressed I knew my legs were toast. The last ten minutes, despite the low power output, was hard work. Suffice to say, the run didn't happen. I wasn't going to put myself into the red and hopefully, by skipping it today, I will live to run another day - or tomorrow as it is know in the trade....