I may not have started any bright and amazing cross training yet, but I have at least stopped screaming. I have also embraced my crutches, which have been gathering dust since I broke my ankle at the turn of the century. All of which means that I have upper body DOMS like you wouldn’t believe.
Arm DOMS, shoulder DOMS, wrist DOMS. I even have armpit DOMS. Did you even know that there were muscles there?
This morning, I also tried some water running (aka aqua jogging). I’m not sure what I was expecting, but I was pleasantly surprised, both by how much I enjoyed it and by how exhausted I was at the end. Whether I can fit in any more sessions over the next five weeks is questionable, but I’ll certainly try.
abradypus 
I don’t envy you. I’ve just got a pesky sore throat/cold thing going on* and I’m fed up already. Good for you for finding something enjoyable to keep you going.
*I am also a member of ‘the niggling foot pain club’ but we all know the first rule of ‘the niggling foot pain club’, don’t we?!…
We do indeed. Though it ought to be “don’t run 21 miles, you muppet!”
aqua jogging sounds fun, will give it a go 🙂