Hi cocob1,
I had to look at how I wanted to workout for just the opposite reason, most of Cathe's workouts were too hard for me to start with, and I didn't have all the ones for her rotations. I chose to look up the principles & methods behind fitness & sports training so I could develop rotations that I could do that would increase my level of overall fitness.
There are many books & free articles about periodization & sports training, you don't necessarily have to be involved in a sport to benefit from that approach.
I generally use a wave type structure in planning a micro cycle (week long, or so), meso cycle (month long), or macro cycle, 3 month (or however) long, meaning there would be an easy month, moderate month, harder month, followed by easy, etc.
There are many elements you can change, focus, length of workout, intensity, impact, plus light, moderate, heavy weights. you get the idea.
You could even use the exact same routine, like say Power Max, do the 6" on Monday the 8" on Wednesday & the 4" inch step on Friday. Alternate with weights like Pure Strength on the alternating days, have a day off or two. Actually might do something like that for August.
Here is one article with some things you could vary during weeks & months,
http://www.unm.edu/~lkravitz/Article folder/periodization.html
Don't get me wrong, I'd love to do all Cathe routines as produced & be able to jump into her monthly rotations, but I think that's a "someday" for me, in the meantime, I plan for things that I can do in a systematic way to prevent injury & get the results I want:
mainly to be "Healthy, Strong, & Fit"
There really is a Cathe for just about anything you would like to do!
Enjoy!
Linda