I'm only doing cardio (but varying machines and patterns) until this all becomes an ingrained habit. Then I'll look at strength training or other options.
The first day I was a total mess, and could barely do 25 minutes on a basic elliptical machine, and my heart rate kicked up to (ridiculous number deleted) very quickly.
I don't bounce back like I used to, but it only took a day or two before my heart rate stopped spiking up to (ridiculous number deleted) at any significant effort, and I was able to start maintaining a lower rate.
About 2 weeks in K had to buy a new heart rate monitor, so I had him pick one up for me too, and that has helped a lot. I was probably overdoing things a bit before that point. I've started using the goal heart rate programs on the machines. I can easily maintain 145-150bpm for 40-60 minutes. I now need to work towards the point where it's more effort to do that.
I've just started working on maintaining a lower heart rate (instead of jumping straight to 145-150) for a significant portion of my workout. I'm currently at 135, and hope to work that down a bit.