You ask, “Are you bored?” Even if you don’t have a gut feeling, it’s a good question to randomly ask your team. When I ask, I look you straight in the eyes and if you can’t stare me in the face and answer, I’m going to keep digging until you look me in the eye.
Bored People Quit.
Worth a read for sure. Sometimes its just as simple as asking the question directly and carefully listening to the person on the other end.