I just told @RainbowC that my run was hard, which it was. Sort of?
It was certainly harder than I thought the 20 minute jog round a local recreation ground was going to be. My body behaved itself during the run - I could feel where I'm still a bit bruised after my fall, but my back muscles didn't go into spasm or otherwise bite me, and the cold air didn't leave me coughing (which I was worried about). But I did feel rather like I was wading through treacle, and I was a bit light headed afterwards (first time that's happened).
Home now, and I've had a glass of water. Next up, lunch and then a slice of fruit cake.