There’s the woman who hit the treadmill so compulsively that she could do little else—and all because, every moment that she wasn’t exercising, the thought of fat cells proliferating in her body drove her nearly mad with anxiety. There’s the actor who was so certain he suffered from a dire illness that he compulsively pressed his doctors to give him CT scans, over and over, to assuage his angst. And there are the millions of us who feel compelled to check our phones before we get out of bed in the morning and constantly throughout the day, because FOMO—the fear of missing out—fills us with so much anxiety that it…