Teaching those group exercise classes looks easy, doesnt it? You learn the routines, climb the platform, turn up the music and off you go, whipping your minions into shape. But to be a truly good instructor takes something more and thats not easy. Katharine teaches classes at Lifestyle Family Fitness in Hyde Park: Body Pump, a weight-lifting session set to music; and RPM, a spinning class. Her style is to motivate through fun, humor and a bit of showmanship. Workout teachers who force out exhortations or try to conjure crowd response (Are we feeling GOOD yet?!!!) often fail. Katharine gets everyone up, smiling and into it without even seeming to try. 1610 Swann Ave., Tampa, 813-258-0500. Ask the club for Katharines schedule of classes.