I recently had a bout of this at my current work.

For a while I was struggling to pinpoint my discontent, but I ended up realizing it was because I felt I was undervalued compared to the contributions I had made over the years.

As it happened, my superiors had come to realize the same, so when I asked for a talk, they preempted my plan by announcing this.

As mentioned by the article, I've since been included in much more strategic talks and discussions to help shape the future of the company, as we're moving our products from the desktop to the web.

It's still something I'll keep an eye on, but just realizing the source of my frustration was very helpful. It also made me more aware of how I shouldn't sacrifice too much unless it's being valued, as opposed to just being more useful.