all i can say is i got more results in my 1st 30 days of P90X than over 10 years of Gym memberships, Bowflex,treadmill, running and dumbells.. it is seriously hard, and it will challenge anyone i assure you. at 50 years old it doesnt get easier getting fit, and P90X is no picnic for sure., but i can see abbs for the 1st time in my life..
i still have 2 weeks to complete round one, and gonna take a couple weeks off and hit it again. my wife(also 50) is doing it, and is also getting results..
I highly recommend P90X if u want a serious challenge..