Happiness is a very subjective thing and it fluctuates all the time for each person. No one is happy all the time.
A more accurate question would be "Are you happy right now?" and to that question my answer would be "Yes, i'm happy right now". But there's no guarantee that I will still be happy next week, tomorrow, or even a few minutes in the future.
Defining "Happiness" puts it in kind of similar situation with "Success". Some people may define "Success" as having a lot of money but a lot others don't care all that much about it. The same applies for "Happiness"
Sometimes we can be happy for no reason at all. Sometimes being content with the things we already have even if it's close to nothing is enough to make us happy. Happiness and emotions in general are still very complex for us to understand wholly.
