I should have blogged yesterday as that is the day I stalled out at 10 burpees. My lower back has tightened up incredibly and I think the burpees are one of the factors going into that. Usually I can get nice and loose in the morning by stepping back into my first few pushups and sometimes even stepping up into a squat position before jumping (instead of jumping into an extension and back into the squat). By 3 or 4 it feels fine to jump back, but yesterday my lower back was unhappy and when I finally jumped on my 10th burpee it got very unhappy. So I stopped. And I had to skip this morning.
I am now down 9 + 20. I take heart in that my sister Joke made up 81 burpees in one day and we have another member who is keeping track of all the burpees she can't do while her shoulder is hurting (more than a 100 last we spoke).
I agree with Rachel, if it weren't for the ability to talk about this thing it would be much more tempting to give up.