It’s your default state – it’s how you feel when nothing in particular is happening. It’s the ‘set point’ some people refer to. It’s the lubricant which makes day-to-day life worth living.
A person with a strong core happiness is glad to be alive.
If a happy person’s house burns down, or if a loved one dies, the person understandably suffers. Their core happiness is swamped by suffering. But midst the suffering they still consider their life to be a happy one. They instinctively know that despite their suffering, life is still worth living. They endure the suffering with the knowledge that at some point their suffering will cease, and their happiness will return.
Core happiness is not about experiencing joy or avoiding suffering – it’s about how you feel when you are not joyful, and not suffering.