Happiness, as in the context of a Hindu (a cultural, subcontinental cultural expression, rather than a narrow religious term) is something that was thought about my the brightest minds.
Essays,Books, Schools, Religions have been built and nurtured on it’s name. Avatars created, Saints glorified.
Yet, for an average human in present day world with it’s plentiful amenities and material distractions, happiness seems as elusive as before; sometimes more so. The Hindu always felt its something that comes from within, our very nature, its always there, not something that’s got from outside. Our cravings, which trouble our mind and if obtained satisfy it merely gives us temporary mental satisfaction which subsides the waves of restlessness in our Chitta (A yogic term, mind-space would be a close translation) which allows the pre-existing happiness to shine through.
A Hindu, views all material happiness as temporary and bitter sweet since all material pursuits are attaching us with action and thoughts in the direction which opens us up for Karma.
So for a Hindu, happiness is our native state which we have muddled with our desires and pursuits.