Mammals are wired to look for novelty in the environment, a behavior called "seeking." Your brain is wired to seek and it gets a dopamine hit each time it does. Dopamine is the same neurotransmitter stimulated by drugs like cocaine and speed. It makes you feel focused, energized, and good at first, but after a while you just feel stressed, sketchy, and burnt out.
The complement to the seeking system is the reward system. Finding the object of seeking, such as food, sex, or shopping sprees, creates opiates - the drugs that calm you down, make you blissful, and unwilling to seek. The opiates counterbalance the seeking, and keep it from getting caught in an endless cycle. The trouble is that evolution did not favor animals that sat around all fat and happy - they were probably the first to become dinner for those others who kept seeking. This means that the system is rigged: there is much more desire to seek than to be rewarded. We would rather look than actually find.
Our ancestors evolved in a world where almost nothing interesting ever happened (lots and lots and lots of quiet time). But now we live in an environment with an endless supply of intense novel stimuli - books, movies, television, music, internet, texting. Our brains are so full! We are stuffed beyond the limit but can't stop pressing the seek button. It keeps us trapped in an unsatisfying loop of always wanting and never being satisfied.
But there's a way out: Every so often take a break from new information. Our brains require some real down time. Down time doesn't mean watching Netflix (which is just a bunch of emotional stimulation and more novelty seeking) or hanging with friends. Down time means deeply quiet, really simple, totally open time in which you are not working, accomplishing anything, or taking in new information. Down time means staring at trees, or strolling aimlessly in a forest. Even in the city, it's not hard to just kick back and watch the sky. If this sounds boring, that's the idea. Give yourself a break from doing, thinking, working, judging, evaluating. Let yourself get bored!