Where has all my energy gone?

Tuesday night.
Seems Tuesday comes more often that it used to.
A lot of people are gathering. Looks like a big class.
I count eight; this does not include the trainer, who is still out in the gym working some “hopeful soul” to exhaustion.
Soon she will be working all eight of us to exhaustion, “building our endurance”, meting out punishment, draining our energy and seemingly increasing her own.
I once saw a Star Trek movie about just this sort of thing. A “creature” appeared on the Star Trek and would slowly drain the energy from those around her, leaving a mere shadow of the person. Kirk barley escaped with his life.
This same scenario has been played out in the new TV series, “Heroes”. It seems one of the entities can absorb the powers of the others increasing his or her own abilities exponentially.
So mid way through the exercise, every one is sweating and breathing hard and moving from one station to station when an “ululation” of triumph and joy explodes form the trainer.
She hops around in time with the background music, actually the foreground music, you don’t miss this music, it is angry and it drives you to and through the exercise, waiting for the next person on the mitts.
I am usually walking around in a “fog” at this point, have stumbled into the trainer, failed to hear the instructions, failed to adequately count past two and gotten lost in an activity and just kept on keeping on.
I don’t think anyone else in the group has to dig that deep into reserves (as they are in much better shape) to get through the paces but each one of them is going full tilt, burning calories and pumping heat and energy into the room.
And here is another clue as to the flow of energy in this class.
At the end of the session, the trainer always thanks everyone for the “good work”. The twinkle in her eye burns a lot brighter and the laugh is a lot lighter as she leaves to “wrestle down” another soul looking for physical redemption and offering her the price of their energy.