You lift bro? How America became a nation of exercise obsessives.

Every week, it feels as if there’s a hot new fitness trend. The classes are full, there’s a line at the squat rack, and there’s a good chance you know someone with a stationary bike in a corner of their apartment. When it comes to how we choose to move our bodies, we have options. But our pilates (and barre and weightlighting) obsession did not come out of nowhere.

That’s where Danielle Friedman comes in. She’s a journalist and author of the book, Let’s Get Physical: How Women Discovered Exercise and Reshaped the World. According to Friedman, we’re living in a fitness golden age, but it wasn’t always this way. In the 1950s, people were actively discouraged from exercising. “For women, exercise was seen as especially dangerous,” she says. “There was a widespread belief that strenuous exerc