I just started Insanity as well. I'm on Week 1 Day 5. So we're pretty much at the same point. I'm fairly fit aerobically so it's not been super hard for me in that sense but some of the plank moves make me want to cry so I feel you.
I think based on what I've read you're supposed to to work at your own pace and even the people in the videos take breaks. Obviously your need for breaks will depend on how fit you are and of course you'll get better.
I know from 30 day shred and other workout dvds that by like the 5th of so time I do a tough workout, everything becomes easier and I begin to feel stronger and more capable so just stick with it and work at your own pace.
: Jan 2009: 275lb; 3FC Start Weight
: July 19, 2009: 257lb; Record Low Weight
: Oct 21, 2012: 152lb
Losing the Regain- Jul 2014- March 2016
Overall Weight Loss