Power Meter Wanted

People need visible power meters.  Maybe not for everyone to see, but to tell, at a glance, how much energy you have in reserve...  Like the ones in video games.  That way, you're not just rolling along and suddenly, without any warning, crash.

It would then be possible to observe the things in life which drain you quickest.  You'd be able to discern how much time you could spend in certain situations or company and still have enough left for the rest of the day.  Before you get involved in something, you could shoot a look at your meter and say, "Nope, not enough left for that, today."

Too bad we don't have something like that.  We're left with vague feelings.  As it stands, crashing on the couch under a comfortable blanket will have to suffice.