I think at every point, people have different yet individual things they are dealing with. And there's nothing as having a shoulder to cry on when you need to. But when an unsolicited care is shown, especially from a Boss, it literally makes the things somewhat bearable.

So yes, the appropriate Question is How are you doing today? But mean it. Dont ask an employee about their welfare and before they get the chance to reply, you are walking away. It's not cool!

You have to build a team that knows you truly care. That way, such simple questions can mean the world to them. It's important