It is not intellectual, or innate. It is not brought about by material wealth or physical pleasure. These are temporary and as likely to cause pain as they are joy.
Happiness, in my mind, is undefinable but instantly recognisable. That’s the beauty of it. It cannot be possessed, yet it can possess you. All you can do is open your heart and allow it in. If it makes a home inside you, with a bit of luck, it’ll visit you often and may even call you a friend?
With a bit of luck.