I just started the P90X system about 3 weeks ago. There is no way that I can follow along to all the exercises at my current fitness level so I modify the exercises to suit my needs and ability. They show you how to do a bit of that in the dvds but some of my modifications come from having taken fitness classes in the past with an instructor. I also take a day or two off here and there as I need it or if there are other activities that I want to do instead of the dvds.
Everything in moderation, including moderation.
2007 Rodriguez Adventure/B72
2009 Masi Soulville Mixte/B18
1997 Trek 820 Step-thru Xtracycle/B17