Pilates is about the same intensity as a moderate Yoga session, but you are mostly doing exercises on a mat, on your back, your side or on all fours and few or no inversions (and when you do something where you head is lower than your heart, you aren't holding a pose). Some DVDs have you doing exercises faster than others, depending on the school of Pilates the instructor comes from (those who stick close to what founder Joseph Pilates taught often do the exercises faster, and it's more challenging this way). Personally, I think slower is better for beginners, since the moves rely on precision and it's easier to get the moves down when you're doing them slowly. You need to move in conjunction with your breath, hold your abs in ("bring your belly button to the spine," as they say... as if most people's belly buttons would come anywhere
close to the spine!
), keep a "neutral" spine (with a natural curve, not exaggerated or straightened out), etc. If you do what the video instructor says, you'll be fine.
The whole key to Pilates is not how many reps you do, but how precisely you are able to do the moves. The precision is what builds up your strength and muscle tone. This is why it never gets easier, and the same moves are challenging even after you've been doing them for months. And it's probably one of the safer exercises for someone with low blood pressure.
-J.
I want it to get a bit easier...I also get dizzy when I'm doing really fast stuff, so I'm not looking for that. I want something that might tone my muscules, but is more relaxing then anything.