Sadness from heartache, happiness at finding a long-lost friend, anxiety before a job interview; you might think you are completely in control of what you feel and that you understand what causes those feelings.

Your brain can be sneaky. Emotions include how you feel and how you process and respond to those feelings.

Your brain and its complex processes are manipulating your emotions. Your brain is affecting how you feel and how you respond to those feelings in ways you’re probably not even aware of.

Emotions like fear serve to protect you from danger so you can survive to pass on your genes. Emotions like Love and lust give you the desire to reproduce.

Neurons send signals through neurotransmitters. These chemicals essentially let the parts of the brain communicate with each other.

Dopamine is related to experiences of pleasure and the reward-learning process. Serotonin is a neurotransmitter associated with memory and learning.

An imbalance in Serotonin levels results in an increase in anger, anxiety, depression and panic. Norepinephrine helps moderate your mood by controlling stress and anxiety.

The two sides of your brain process information differently, they work together to keep your emotions in check. The right hemisphere identifies, and the left hemisphere interprets.

The right brain identifies negative emotions, like fear, anger or danger. It then alerts the left brain, which decides what to do interpreting the situation and making a logical decision about how to act in response.

Without the left brain, the right brain would be overcome with negative emotions and not know how to respond to them.

And without the right brain, the left brain would not be as good at identifying negative emotions.

Memories of previous experiences influence how you respond emotionally to situations. If you once nearly drowned, you might experience fear around water.

If a previous Love had a wandering eye, you might feel jealousy when your current flame looks at another person.

A soldier who has had extensive combat experience or traumatic combat experience will likely have more intense anxiety later on.