It's varies from one individual to another. What constitutes happiness for one person may not be all that important to another.
Without a doubt it's difficult for most people to be "happy" while being in poor health or lacking a certain amount of "creature comforts".
It's human nature to always have a (desire) for something you don't have. It gives us a reason to get out of bed or have something to look forward to. We replace one goal with another.
Some people are happy if they have healthy loving relationships with friends, family, spouses or "significant others".
Generally speaking "happiness" is a temporary (feeling of elation) that "all is right" in one's life. It's usually fleeting.
Being (content) is far more common.
Things like being cut off on the drive home can easily change someone's mood or hearing about a horrific news event such as 9-11 and Hurricane Katrina which may have no (personal) relevance to you but it makes you unhappy. Happiness is a moment in time most often acknowledged in the past tense.
Truth be told there is always something horrific or some atrocities going on around the globe. "Ignorance is bliss".