And your point about being you in mid-fifties is?!?!
If you like DA, add a boot camp DVD....though she loses a lot of credibility when I review her DVD list. This is specifically due to 'spot' reduction DVD's.
Try the The Biggest Loser: Cardio Max and The Biggest Loser: Power Sculpt DVDs. They offer what seems to be a great cardio and light stregth element (mostly body weight).
Don't get me wrong about DA, I think the one you have is prabably one of the better DA DVDs.
I would do the BL cardio DVD on Monday, the BL Sculpt on Wed and the DA Pilates DVD on Friday. On Tuesday, Thursdy and Saturday I would go out the door for a jog/brisk walk for of at least 45-60 minutes.
If you want to step it up, one of the best set of DVD's out there is the P90x DVD's. While really advnced if performed to the fullest extent, there is an option to perform the 'Lean" routine. Not near as much strength but more cardio. Tony is great about pushing the reduced as well as more advanced modifications to each move.
Oh, I am 52 so that is why I kind of push the mid-50's comment. Remember, only go as hard as you can - but push within safe ranges past the initial point of wanting to quit.