Rest Days on Insanity

In the first month I think some light exercise, like a light walk, is ok. In the 2nd month (I'm on my last week) I needed the rest day for my sore arms and abs. I didn't do any further exercises.

Personally, I got horribly bored with 6 days of Cardio Core & Balance so I took 4 days off. I wouldn't supplement but maybe find something to add on for stretching. When I do another round later in the year I'm going to sub with some type of yoga and alternate CC&B and Yoga on those 6 days or just skip it all together and jump into the 2nd month (only because it won't be my first time doing Insanity).

I say if you feel fine, go for it. i'm on the second to last week of Month 2 and I haven't been taking rest days either. Listen to your body

It's totally up to you, you will know when you definitely need a rest, on my rest day, which is a Sunday, I normally do a leisurely walk for a few hours. I did also get bored with 6 days of core cardio and balance and did throw in some Jillian Michaels workout for a laugh. Month 2 is very tough, I thought, I do take it easy on my rest day. Good luck with your workouts. I am on Round 2