How do we define happiness?

How do we define happiness? In psychology terms we see this as a behavioural state but in neuroscience terms this is seen as a difference between a higher and lower happiness arousal state, which we tend to call peaceful. The higher arousal state is not sustainable as it is a high energy state and so it is true that we cannot be happy all of the time. We need to aim for that more steady state of what we refer to as peace or trust.