I'm almost two thirds of the way through right now. Started my second recovery week today in fact. I started off thin except for a minor beer gut. Now I'm rail thin through the stomach and cut like I've never been before. Not saying that to brag, but just saying, the flat out works. I was amazed after three weeks at the change in my physique. It's an awesome program.
Even if you're fit, you'll need to take some time before you jump in. I was in decent shape, but I spent three weeks sore as , skipping/quitting workouts, having ty form and generally faking my way through it before I realized I'd really been failing and needed to start over. I did that and ever since, haven't missed even part of a workout. You can't half-ass your way through it. So I'd say spend a couple weeks familiarizing before you officially start. I also made a point to start on Sunday, cause as a product of the weekend, Sat is the one day I'd like to be able to rest and go out and do , without worrying about having to do p90.
I'd suggest adjustable dumbbells as well. I use everything from piddly little 5 lbs for a couple things all the way up and between to 45 lbs for some of the shoulder stuff. I'm sure stronger dudes would need more. So if you're that, get more. I wish I had more for a few things, but I don't yet. And I don't have a nice dial up set, just bars and plates with clips to hold them on.
I haven't followed the exact diet per se. I was already pescetarian with no dairy or processed ty foods in my diet. I've looked at it though, the first phase anyway: it's basically all protein (lean as possible) and vegetables. Almost no fat, sugar or carbs. Which means very little fruit, bread and rice. Don't even think about soda and candy. All I've had/tried to do is cut the out of my carbs. Not following the exact plan, but all I'm eating is fish, beans, hemp protein, vegetables, hemp milk/orange juice and water. I'm still drinking beer and whiskey, which is where I'm getting any carbs from, in addition to the OJ I mix with the hemp protein. I find it tolerable, but yeah, I was almost there before I started.
You need to find a chuggable protein source. Hemp protein is the only way to go tbh. Even if it's more expensive. Whey is re ed. Reading on such here:
http://www.proteinbreakthrough.com/