I've done level one of the 30DS about six times now. I was improving and only had to take short second breaks for breathing when I took two days off because of sheer laziness(bad, I know.) I finally got back on board today and thirteen minutes in I literally had to stop the exercise because it felt incredibly momentous all the sudden and it felt like I'd been going for an hour! I got really heated, sore, and sweaty and just couldn't do any more. I can always push through exhaustion but I literally couldn't this time around.
What do you guys think happened? I've never struggled like that with this exercise before.