well, try this on for size, i took for two weeks prior to when i have to run a steadicam rig (look it up) man oh man, I can do shit superman would be jealous of, they called me hulk. after run throughs on stairs with a full running rig, i got really hard, cut up, and was doing inhuman moves.
see hold a full bottle of milk, now start to move it away from your body until it is at arms length, now try this with a 25lb camera, while running up three flights of steps, and keep pace with a very athletic heavily trained 'diesel' powered actor.
halo no shit dude, everytime i do this and have three days of shooting, i am a god.