I think those warnings are to protect them, so that someone who is terribly unfit and decides to do the video three times in a row doesn't sue them when they have a heart attack. I do think you have to go slow, and do only part of each exercise, and maybe not the whole video, when you start out. I did one once, for a short while, and I divided it in two. I did the warm up and cool down every day, but alternated the first and second half of the video,