This is the question of Sukkot, the Festival of Happiness. It is the question of life, for we are all in pursuit of happiness. What is it, and how can it be attained?
What does Judaism think?
There is a shortcut to identifying what is NOT happiness. And perhaps by defining the forgery, we'll be able to zero in on the real thing. (No, Coke is not happiness, nor is it the "real thing", unless you are looking for low grade poison). So what is NOT happiness?
Anything the includes a "when" or an "if". "When I get that job, I'll be happy" is a falsehood. "If I win that girl I'll be happy" is simply not true.
You see, happiness that is dependent on anything external to the person cannot be true happiness. That is because Judaism teaches that happiness should be part of our daily lives. How can we be demanded to do that if we can't control the the things that are supposed to bring us happiness?
The Mishna defines rich for us as one who is "happy with one's lot". That is not to say ambition isn't good. It can lead to great accomplishment. What is not good is greed and jealousy. Defining happiness by what we do not yet have taps right in to those negative traits.
And it keeps us unhappy in the meantime.
So what IS happiness?
It is knowing your place in the universe. It is not being the first baseman for the St. Louis team in Abbott and Costello's lexicon. That first baseman is named "Who", a person so disconnected from their identity that they don't even have a defined name! (Of course I doubt A & C meant that, but I'll take a literary license.)
My teacher, Rav Ahron Soloveichik, taught how each person has a "True I", an inner essence and identity. That identity is understood by understanding where we fit in in the universe. When I am deeply aware of where I came from, what people and land is mine, and what is our destiny and mission, I am deeply connected. It gives my life meaning and direction, and that breeds the truest form of happiness.
No wonder that the Talmud claims that there is no joy greater than the resolution of doubts. True joy comes with knowledge and connection.
This is the meaning of "Who is rich, he who is happy with his lot." A "lot" can refer to a portion of a field, a place that is relative to and connected to another place, and thus to the whole field.
The world is the field, and when we know and embrace our portion of it, we are happy and we are truly wealthy.