Floor Work Makes My Back Hurt

[goattrainer]

I posted this over in the more viewed area, but I think this might be a little more category correct. :-)

I just got "Fat to Firm Fast" with Michelle Dozios, which I really love!

Anyway, when she does the floor exercises that involve laying on your back, I am so uncomfortable that I can't do them. They really hurt my lower back. Same when I tried Pilates floor moves, especially when clasping my knees to my chest and rocking foreward and backward (with the spine in a "C" shape). Needless to say, this knocks out a whole lot of exercises that I want to do.

My floor is hardwood with a rug on it about 1/4-1/2 inch thick.

Any suggestions? I was thinking a floor mat might work, but since just laying on my back hurts my lower back, do I need a really thick one? Is some type of yoga mat going to work?

Thanks,
goattrainer

PS Any spacific product recomendations would be great!