I had a boss once who when he wanted to convey how serious he was he would remind the staff we were at work. This conversation would usually ensue if he noticed that too many of us looked like we were having a good time. His point was that if we were really working, we wouldn't be having any fun. Work was not to be thought of as enjoyable. That's why they called it work, he told us. If it wasn't they would call it play.
Work takes on a negative connotation in the contrast of play. Work becomes tiring and boring. It becomes something we have to do and not something we want to do. We sludge through to get it done so we can go play later. It's what happens Monday through Friday in specified hours. Work now and play later. Forget any enjoyment. No smiles, please. Who really wants to work anyway? Work becomes a four letter word.
But then, so is Play. And if you are working at what you love or at the very least love what you are working, the lines get pretty blurred. You still can feel the euphoria of Friday and the break of a weekend ahead, but you're not going to dread Monday morning. Or if you're like me you might occasionally do your work all day Sunday and take Tuesday as a rest day.