Mpr News With Kerri Miller

Historian Natalia Mehlman Petrzela was a self-proclaimed bookish kid growing up in the 1990s. She didn’t exercise, she didn’t play sports and she loathed physical education at school. But that changed when she first stepped into a group exercise class. “When I walked in there, I discovered there was something called fitness,” she tells host Kerri Miller on this week’s Big Books and Bold Ideas. “Pretty quickly I realized this is not only better than PE, I love this. I don’t just tolerate it.”So began a shift within Petrzela. She started to move her body and like it. She became a fitness instructor and taught classes, even as she ended up working in academic. And as a historian, she couldn’t help but look around her secondary world and wonder: How did this fitness culture come to be?Her new book, “Fit Nation,” is the result of digging in to that question. The book charts the evolution of our collective attitudes toward exercise. From body builders on the beach in the 1940s, to Jack LaLanne introducing exercise