Besides fear, discontent is probably the most prevalent emotion we all have in common. It's a low lying dread in the back of our mind that's constantly dissatisfied with the present. We are always looking for something to change or improve. Nothing is good enough.
Just recently, as I was on vacation I noticed a dull negative emotion deep in the back of my mind; even as I tried to remain present and enjoy nature and quiet time with my wife. Everything was just as I wanted it, but there was a lagging worry or anxiety I couldn't put my finger on. Interesting.