we feel before we think.  However, if we speed up or strengthen the cortex's natural ability to inhibit the limbic system, we can change our feelings before they have a chance to impair our behavior or judgment. In a review of studies bearing on this very question, a team of Brazilian neuroscientists headed by Patricia Ribeiro Porto (2009) concluded that cognitive-behavioral therapy in fact does change the neural circuits involved in the regulation of anxiety. Other studies have, similarly, shown beneficial effects of cognitive and cognitive-behavioral therapy on the neurobiology of negative emotions. Many people think that the only way to change your brain's chemistry is through medication . These studies provide clear evidence that you can change your brain's chemistry by changing how your brain interprets the data it receives from your limbic system. Cognitive-behavioral therapy not only has fewer side effects (i.e. none) compared to medication, but it produces changes that can last for years, if not a lifetime.  After you learn to change the way your limbic system reacts, you have less reason to worry because you're not processing your experiences the same way anymore. Sometimes it's actually good to worry, especially if there's a real danger lurking in the shadows. You should worry about losing your job if you're continually late for work, or about losing your partner if you're unfaithful. However, apart from these obvious situations where worry might be warranted, just as often it is not. As Ropeik pointed out, we sometimes place too