Initially, I tried folding up some spare blankets at the foot of the bed, under the sheets. No clue about it having any cardio-benefits, but it certainly did a smashing job at hyper-extending my ankles, so I'd hobble around like I'd tripped in a gopher-hole the day before.
Remembering someone talking about inheriting a bed from their grandfather, who had sawed a few inches off of the headboard-legs of his bed, I tried propping up the footboard-legs. So it wouldn't suddenly throw me for a loop, I made a point of starting with one 1" block under each leg, then another block a couple of weeks later, then yet another one. Didn't seem so bad, other than the majority of folks getting in or out of my bed stubbing their toes on the blocks.
Just last night I was checking for something under my bed (PS: Nope! No monsters found) and realized that my mattress isn't actually supported by the frame. See, it seems it's on a really basic metal frame with wheels, and that is set into the wooden bed-frame (with the headboard and footboard and all). So the reason why it didn't seem that much of a change to jack the bed up was that it wasn't actually jacking anything up, except for the frame around my bed.
With a little work, I managed to hoist up the thing the mattress is on and jam blocks under the wheeled legs, so I should have more to report in the future.
PS: My auto-sphygmomanometer seems to be feeling out of sorts, so no BP/Pulse Mood entry, this time.