I have a couple of dvd's that I try to use a couple of times a week (although I don't always get around to it). It's in addition to what I already do. I have the Billy Blanks Taebo Abs dvd which I've found is a great source for a core workout (I feel it in my abs, obliques, and even in my back and shoulders). I don't have foot pain when I do the dvd but I can't always keep up. So, I either stop the dvd or I'll put in a pause so that I can catch my breath a bit. What's my point? You can always stop the dvd for a few minutes.
Are you doing high impact exercise everyday that you do cardio? If you are, you may want to consider alternating between high and low impact. I use the treadmill, elliptical, rowing machine, and stationary bike at the gym. I can still get a good workout on each of these machines without having to be a high impact. All I do is adjust the resistance or incline along with adjusting my speed. Basically, you could do the high impact 3x/week and then do low impact 2x/week (like leisurely walk, even if you have to walk for an hour).