The Glen Arbor Athletic Club will soon open its doors to locals who want to trim down or beef up in the same historic two-room school house where students were once asked to listen up and jot down notes. Two couples, Paul and Marcia Walters and Terry and Linda Gretzema, who have summered here over the years and now consider themselves permanent locals, stumbled on the idea of opening an athletic club when they realized they wanted to stay active, somehow, during their golden retirement years up north. And what better way to keep the flabs at bay than by working those abs every morning.