Hi Angelmagic! Good luck on the 21-day! I've never heard of it. I can't do it with you, because I've already developed a plan I'm sticking to (with the exception of the 3-day diet) and I'm going on vacation next Friday for 10 days and I KNOW I'm not gonna do lots of exercising on vacation!
But I hope you do well on this - report back & let us know!