Before the beginning, the Talmud tells, the Creator consulted each of His creations.
He asked the lion, “Would you enjoy being a lion?”
He asked the worm, "Would you enjoy being a worm?"
And only after each thing agreed, only then were they created.
The Talmud is not interested in fables. This is its way of telling us that G‑d shares His delight with each of His creations.
Just as He delights in bringing each of His creations into being, so each creation delights and celebrates being just what it is.
Indeed, that delight and that joy is the very essence of each thing.
And our job? To uncover it and let it shine.
I see a lot of answers here that are challenging the "happiness" theme. And I'm glad. I'm glad that finally, people are starting to wake up from the "positivity" dream that has been shoved on us for two generations. This dream wasn't for our good, it was for the good of leaders who would benefit greatly from getting everyone to sacrifice, strive, ignore their needs and the needs of their families, in order to fulfill the leader's plans. Religious leaders, bosses, government leaders, teachers, etc., have been demanding more and more, whipping us into a frenzy of production, while our personal and spiritual lives crash. Enough. Let each of us seek our path directly from HaShem and His Torah. It won't all be "positive", but it will have meaning to us, and that is what gives true joy, not transient "happiness".