I'm getting both bored and anxious if I don't have anything useful to do during work hours. I don't think it's my work ethics in the play, but self imposed expectations. When this happens too much too often, is when the work no longer feels "fun" and I have to find something meaningful to do again.

Now I'm very privileged in that my current employer's been very good with the opportunities within, and I've always found another position (and promotion) to challenge myself again.

But I think many people expect their work to be interesting, feeling meaningful personally, and if it fails to do so it's time to move. It's crapton of your week anyways you need to spend on the "grind" it would suck if it felt wasted time.