Before you begin the program, you should take the Fit Test, which gives you a baseline for the minimum you should be able to do in order to begin with the P90X workout plan. The Fit Test is outlined in the Fitness Guide, a book that is included when you order the DVDs. If you've lost your Fitness Guide or want a preview of the Fit Test, you can go her for the P90X Fitness Guide pdf.
Another integral part of the P90X workout isn't about working out at all... it's about eating right. Your guide to this is the P90X Nutrition Guide.
To do P90X, you won't need a huge space.... the area between your couch and your TV will probably be enough. There are a few exercises where you need to cover some ground (think the running through big tires drill you see football players doing), but generally a 6 foot by 6 foots space should be just fine.
You can read about the equipment needed here.
You have options when doing the P90X workouts... you can choose between the Classic, Lean and Doubles programs. P90X Classic routine is the program most people do when they begin. The P90X Lean program is for those who want a more cardio-based and slightly less intensive program. Don't be fooled, Lean is still very challenging.... I lost my first 25 pounds with P90X doing the Lean program. The P90X Doubles program is basically for those who wants to do super extra workouts and double up some days with some extra cardio.
It takes about an hour a day, 6 days a week. The 7th day is a rest day, or you can do the Stretch X DVD. Just think of all the time you'll save not going to the gym. In an ideal world, you'd be able to finish all 90 days in a row. Most people don't. Opinions vary on what to do about this, and there doesn't seem to be one right answer. If you miss one day, probably the best thing to do is just pick up where you left off the next day. If you miss 3 or more days in a week, you might want to consider starting that week over. If you miss a week or weeks in a row, you might consider starting that phase, or the entire program, over, depending on how far you were in and how you are feeling.
Not sure if P90X is for you?
You might like these alternatives:
Power 90: The predeceasor to P90X. If you complete this, you are in good shape to start P90X.
Turbo Fire: Cardio workout with trainer Chalene Johnson, fired up with great moves and AWESOME music.
Insanity: It's, well... an insane 60 day program that will bump your athletic performance up a bunch of notches. Or more.
10 Minute Trainer - also by Tony Horton, for those seriously time-deprived
Slim in 6 and Brazil Butt Lift are also popular. You can check out these and all the other Beachbody workouts in the Beachbody store.
There are workouts for ALL levels of fitness, please ask me if you need help choosing.
What do you follow the P90X workouts with?
There's a lot of choices... you can do one (or many) more rounds of P90X. There is a P90X One-on-One series, as well as P90X Plus. P90X2 is also available.
Many people also follow P90X with Insanity, or do a hybrid of the two. P90X also hybrids well with Turbo Fire, and you can find those P90X hybrid schedules.