What's missing in your life?
Perhaps it's something you never think about; you see it every day struggling for life next to a busy street, or peeking through an abandoned building. You probably see it in the park but it doesn't occur to you to bring it home, even though it's one of the easiest remedies to anxiety, depression, or general malaise.
Perhaps you should get a plant...
As of 2009, 93% of teens and 77% of adults were online and spending far less time outside or in nature, according to a Pew Internet Project Report. More and more research has been emerging on the positive psychological and physiological effects of greenery in our every day lives by visually enhancing the space and improving air quality. We evolved in nature, and the sudden change in that environment to city living has created what is called "discord: a mismatch between present living conditions and the environment of evolutionary adaptation that has a negative impact (i.e. stress) on well being." 
The absence of plants may unconsciously indicate to the brain - which evolutionarily has not caught up to our busy, modern lives - an unsafe or unfamiliar environment. The very act of looking at a plant or green scenery "decreases activity in the subgenual prefrontal cortex—a part of the brain tied to depressive rumination."  Other studies have found a positive impact on attention and performance in the work place. Living walls, indoor plants, landscaping, and urban planning are quickly becoming the new antidote, or at least co-antidote, for the rise in anxiety and depression.
So, if you're experiencing such 'discord' in your busy, urban life here are a few solutions:
don't forget to take a walk in the park