You feel blue. So she gets you up off the couch to see a movie with her, and you feel better.

Or you don’t feel better. She thinks you should try more talk therapy, which you do, and you feel better.

Or you don’t. You are not blue anymore, just very tired. After half an hour of digging in the garden, you must lie down. At a dinner party the conversation takes too much effort, and you have to excuse yourself. This fatigue goes on for months. She tells you to see your doctor. He reviews your blood work and says you’re fine, and you feel better.