Wander around the Hamptons or Tribeca and you might notice solitary men in T-shirts explaining their solitude: MY WIFE IS AT TRACY. Ordinary people like me can do prerecorded workouts online for $90 a month, but membership at one of Anderson’s studios is a status symbol, the fitness equivalent of waterfront property. Her empire includes eight locations: in Manhattan (one in Tribeca and one in Midtown), the Hamptons (one in Water Mill and one in Sag Harbor), Los Angeles (one in Studio City and one in Santa Monica), and Madrid. Her newest studio is in Bozeman, Montana.