Scooby Doo Where Are You #65

"When the gang's weekly aerobics class at their local gym is interrupted by the ghostly Fitness Freak, shaping up turns to freaking out! Suddenly, the gym's patrons can't get away fast enough. (Too bad Scooby and Shaggy forgot that stationary bikes don't actually go anywhere!) Can Scooby and the gang crack the mystery? Can they unmask the Fitness Freak? And, most important, can they do it without breaking a sweat?"