Whilst wondering if it might be possible to substitute petrol for water in the human body, so if the tank goes empty, you can just ask bystanders to pee it in, and so get to your destination, I came up with a better idea.
I was corrected on whose version of spelling is more authentic, America or British
English and I wanted to say "I stand corrected" but obviously I was at the computer so sitting down at the time.
The device is a series of sensors on the joints, that gives an accurate real-time reading of posture. This can then be used in some dynamic HTML-y code to provide real-time-ish indications of user posture, so it would have automatically updated "stand" to "sit".
As a further add-on a sensor head band, with a tilt sensor would be useful. Initially I was thinking of leaning the head to the right to cover "I am inclined" and vice versa for the left. But, realising this would have to be reversed for countries which drive on the other side, then tipping the head forwards would be a more universal "I am inclined to..." and tipping the head back for "I'm not inclined to...".
Obviously this raises its own issues, but by mapping the user location against dental clinics should rule out a fair number of false readings.
I would also suggest am 11pm-8am local time override to avoid those spurious readings from the body moving while asleep.