Dr. Jill Bolte Taylor writes in her book My Stroke of Insight,
Personally, I really like the way happiness feels inside my body and therefore choose to hook into that circuitry on a regular basis. I have often wondered, if it is a choice, then why would anyone choose anything other than happiness? I can only speculate, but my guess is that many of us simply do not realize that we have a choice and therefore don't exercise the ability to choose. Before my stroke, I thought I was a product of my brain and had no idea that I had some say about how I responded to the emotions surging through me. On an intellectual level I realized I could monitor and shift my cognitive thoughts, but it never dawned on me that I had some say in how I perceived my emotions. No one told me that it only took my biochemistry 90 seconds to capture, and then release me. What an enormous difference this has made in how I live my life.
Another reason many of us may not choose happiness is because when we feel intense negative emotions like anger, jealousy, or frustration, we are actively running complex circuitry in our brain that feels so familiar that we feel strong and powerful.
It is just as easy for me to habitually run the happiness circuit as it is for me to run the anger circuit. In fact, from a biological perspective, happiness is the natural state of being for my right mind. As such, this circuitry is constantly running, and is always available for me to tap into. My anger circuit, on the other hand, does not always run, but can be triggered when I experience some sort of threat. As soon as the physiological response as passed out of my blood stream, I can resume my joy.
The same goes for other emotions, such as fear and anxiety.