RE: Okay Jillybean . . .
Good for you for taking the I-Max and CK plunge! I haven't done CK yet, but I have the feeling it's on the agenda.
With respect to I-Max, give yourself time and practice to work into the intervals. Cathe does demonstrate modifications for the toughest ones that you can go to if you're starting to flame out; use these modifications as needed! The thing I love most about I-Max is that it forces you to recruit the thigh muscles (quads and hamstrings) and gluteals far more than traditional step routines with the plyo intervals, so not only do you get some deep, deep cardio but also leg muscle conditioning!
Also, if you don't have a good, consistent leg strengthening program already in place, start doing so. That will help you with I-Max performance as well as overall performance and health.
You go, girl!
annette