I am starting my 4th week of Insanity and, I agree, the warmups are tough! My only complaint is that after 3 weeks, I am tired of the exact same warmup routine on almost every workout. I am almost looking forward to the 2nd month just for something different. Of course, I am not sure I will make it through 55 minutes of this craziness! Today was the first day I wore a HRM during my workout & wowee...I think I was over 155 for most of the time!