The answer is, of course, sweat. During the production, we made sure to have hair & makeup apply a liberal dose of water (aka "fake sweat") to the fitness model during filming. We took care to capture shots that showed the intensity of the workout as well as the sweaty aftermath of the cooldown. Then we edited the video using an energetic, extremely fast-paced style. The result is a video that conveys the grit and grind of a high-intensity workout as well as those satisfying moments of sweaty, post-workout exhaustion.