Kara - Exactly what ChocoTaco said, never sacrifice your form. Even though Insanity is high impact, work at your own pace. The more you do the workouts your body will get used to it and it won't be as difficult, but it's always gonna be a challenge. That's what the program is designed to do, challenge you.
Cherina - I was also scared before I started the program, but no matter how hard it is DON'T GIVE UP! If your looking for amazing results, you'll get them with Insanity as long as you push play everyday and eat healthy.
Good Luck ucfjennifer! You got this!
In case any of you ladies are interested and since you already own Insanity, I have a free accountability group on Facebook that your welcome to join if you aren't already tied into a group. I'm a Beachbody coach and it's free, no strings attached. It's in place for accountability and to let you know that you are not alone through your weight loss journey. We check in daily with our workouts, share meals, recipes, tips and encourage one another. I don't know that I would have completed my program without the help of the group that I was in. If your interested you can email me at shayla(at)shayla-j.com and from there I can get you all set up