When 24-Hour Fitness shut down its cozy, beloved “Fit-Lite” location on Piedmont Avenue last November, locals were heartbroken. Where else could a gym hater get a cheap, quick, and kick-ass workout without a single sweaty, grunting heavy-lifter in sight? And then came Flex. The new gym’s owners wisely stuck with the thirty-minute circuit training theme — a stunningly effective mix of weight machine and cardio stations, whether you’re a fitness newbie or marathon runner who is fed up with traditional gyms. The interior was treated to a sleek makeover, new types of cardio machines were added to the mix, and members were soon invited to mix it up with twice-weekly boot camp classes at a nearby school. But, in a stroke of brilliance, some things didn’t change — like some of the stellar employees from the Fit-Lite days, who keep the gym and its diverse clientele in fabulous shape.