I think someone has plugged me back into the mains.
Since yesterday, my energy seems to have returned. Obviously not quite back to pre-operation levels, but pretty good none the less. Today, I managed to do some teaching preparation first thing, get myself into the office (partly on foot, partly by bus), deliver a two hour postgraduate seminar (in a seminar room on the 5th floor when only the lift to the 3rd floor was working so I had to walk up and down two flights of stairs, but the views and the blip were worth it...), meet a friend for a coffee and chat, do some teaching preparation for next week in the afternoon, and then go to Hatha yoga at Projekt 42.
I did feel tired walking back to the flat through Jane Street, so brought my stick into play, but overall I was pretty pleased with what I achieved during the day, and both my physical and mental states.