Very overweight and/or obese people trying P90X?

I started P90X classic yesterday. My starting weight is 210, and I stand tall at a whopping 5'2". I've lost about 30 pounds since last June without doing anything extreme (just adding exercise and a few diet modifications), and kept it off even through my lack of activity during the holidays.

I've done jogging, zumba, various aerobics, various calisthenics, spin class, weight training, workouts with my husband that were a mixture of cardio and weights, and all sorts of things over the years. Tonight's Day 2 plyometrics was the hardest thing I've ever done. I have weak knees and ankles and even with modifications, my knees are still on fire two hours later.

The thing I like most about the program is that you can modify according to your abilities. So yesterday on day one, I was lucky to do 7 assisted (with chair) pull ups and about the same amount of push ups and that was on the knees. But I'm already eager to push myself to do more next time that workout comes around. Tony Horton really does a good job of motivating you and he made me feel better about the fact that I could only do about 30% of what they did. By the time I got to the ab ripper, I was really discouraged by how weak my core is, I could hardly do any of them correctly and when I could, I certainly couldn't do 25.

Tonight's plyometrics was a little better because I could actually do most of what they were doing (modified for very weak knees and ankles) even though on some I reached my max a few seconds before the set was done. But I like that they tell me it's hard and remind me that that's the only way to get results. I think if it was marketed as "fast and easy" then I would be very discouraged. Instead, I just do my best "and forget the rest."

P90X sounds like a great program to lose weight, but it's not something you would wanna do the rest of your life. My thoughts are that it's better to get into a regular fitness routine for good... not just for quick, initial results.