Maybe another Cathe-beginner can encourage...
I just bought the dvd for Rhythmic Step, etc.
Like you, I'm a longtime "firmer".
The choreography is tough!
I've just been doing a warmup, then taking a section at a time, and doing it over and over for however long I want my "cardio" time to be. When I'm comfortable enough, I take another little section and add it to what I do over & over. Sometimes I skip ahead to another section so that, when I can do more of the whole workout, I'll reach some points where "I've done this before". (Does that make sense?) Sometimes, my brain & body start to feel fried from the choreography and then just for a break
I'll jump on my Nordictrack and do that for awhile while I watch the next section; if I didn't have a Nordictrack, I'd just march for awhile or do jumping jacks or something while I watch. When my cardio time is up, I do a cooldown.
Even though I'm not new to exercise, I'm new to Cathe, so I'm just letting myself be a beginner and taking it a bit at a time. I haven't done the workouts you're on, but hopefully the principle can still be applied so you feel good about the new stuff you're learning.
Also - appreciate how much you've learned to do already! This morning on eBay I saw a set of Firm tapes for sale by somebody who said those tapes were too tough for their fitness level... I guess the fact that they're selling them, means they don't expect to reach that fitness level, either...
Chris