‘French Sunday’ is the latest viral happiness trend. Here’s how to do it the right way—and boost your productivity all week

If you think Paris is always a good idea and the French do everything better, especially leisure—then this one is for you.

Unlike Americans, who treat their weekends as a sprint to see who can do the most chores, Sundays are sacred in France—a time to slow down, reset for the week, and do as little as possible. “Even protests in France happen every day except Sunday . . . that’s how sacred [they] are,” Céline Kaplan, cofounder of upcycled products marketplace OOOF (Out of Office Forever)...