Hey Tara,
good advise above, watch Ally and modify the moves as you feel needed. If you bring the intensity you'll still be getting a great workout. I did a Turbo Fire/P90X hybrid and due to a past back injury (threw the disc out) and some knee pain I modify what i needed to modify. Basically I kept it on the ground and did no jumping or very little.
Got a great workout - and tons of fun... really like Chalenes HIIT workouts - can work them into any schedule - even the crazy days!
If you're looking for some motivation and a great group of people to chat with on the boards I've started a new thread for people who have a program recently - we have lots of P90X'ers , Insaniacs and others.
Check it out,
message board thread linkCant wait to hear how you like the program.
Coach Donna