Sometimes, we have a blah day or two. Maybe a week, even. Perhaps we’ve gotten some bad news or work is really tough or financial woes are keeping us up at night. We might even say we’re depressed, but we can feel depressed without having clinical depression. So what’s the difference?

Often the distinction comes with how long we’ve been feeling low; blue; tired; unmotivated; numb; down or just plain miserable and how difficult it is to pull out of the fog. There are also some risk factors inv...