Redoing week one and, I may be kidding myself, but today it migh have been a trifle, the merest trifle, easier. At least, while I still couldn't run all the intervals, I managed to run a little further than last time.
However, during cool down, I was struck with a severe headache. I think I was underhydrated, so I'll be more careful next time.
I suspect I'll have to do week one several times