My workout today included a cross training segment of 500 Kcal on a precor
556i (elliptical trainer.) I like this machine. It is elegant and well made,
and I especially like the fact that it is standalone: there is no electrical
cord, because part of the energy the user provides powers the
machine's electronics. There is something appealing about having some
fraction of my power output harnessed for a (slightly) useful 
purpose instead of being wasted as heat.

Of course, I'm sure there is still quite a bit of waste, since
my power output is more than sufficient to light up few leds. Wouldn't
it be great if some exercise machine of the future were able to convert all
of that lost effort into a few grains of some valuable substance, gold
perhaps, which we could later redeem for money? Exercisers of that era might
always carry a small satchel tied around their waist to collect the nuggets
until there is enough to bother cashing in.

A romantic image, but we already have a more mundane technology to reward us for
our efforts! There is a law on the books that requires power companies to buy
power from their customers, if they produce it. If you can produce enough
power, say from a backyard windmill, to spin the power company's meter
backwards, then at the end of the month they owe you money. Why couldn't
Precor or some other company produce a machine with a cord, but one through
which the trickle of power produced by the user is fed back into the power
lines? Imagine it: You swipe your credit card when you mount the machine,
and at the end of the workout your account is credited for the few pennies 
worth of power you pumped onto the grid.

Listen up Precor and Niagara Mohawk: I want my money! It's no more than
fair.

Come to think of it though, this fairness thing, if properly implemented,
should include some accounting for the additional resources (oxygen, e.g,)
I consumed during my workout, above and beyond what I would have used
had I been, say, sitting quietly at my desk. In addition, there should be a 
small fine for the extra waste products I produced (carbon dioxide, etc.) 

Taken to extremes, in the presence of unlimited technological monitoring
capability, this whole idea of fairness becomes a bit scary. In the 
future you might be implanted with an electronic device that
monitors your consumption of _everything_ and adjusts your account
accordingly. Why limit the monitoring to physical things? It is
conceivable your mental state could be monitored, with payments or deductions
based upon how it compares with some baseline state - the state you are in,
say, when sitting at a bus stop staring blankly at the curbing. 

Allowed yourself a moment of elation during your walk to work on a nice Spring
day? It'll cost you. After all, you should expect to pay for what you get
out of life. It's no more than fair.