That reminds me of something I went through when I was 7. I had this gym teacher named Ms. Tucker. She would force all the kids to run, and one day she ran me so hard that I threw up. I joked while I was in the nurse's office that I now understood why they called it being "tuckered out."
She didn't make me run anymore after that...
I don't know how it works over where you are, but I know that, for me, P.E. wasn't a real grade and that they'd pass you for effort even if you did everything wrong consistently. So I just did the parts of the workout that I could do easily, and did a very, very sloppy and easier imitation of the other parts. If I was corrected, I'd pretend not to know what they were talking about... eventually they'd just give up and let me do it my way, giving me a passing grade.
So basically, if you can find some way to make it look like you're trying, but can't do any better, they should eventually just let it go... unless they're extremely anal, nosy jerks.