But if you ask different individuals what is happiness（what happiness is）, there are absolutely a wide variety of answers you would hear. It is difficult to define happiness because it means different things to different people.
Usually, happiness can be described as a feeling of pleasure or enjoyment, some people think that whenever and wherever they would be involved with happiness if they feel happy.(I don't queit follow your meaning here, i do not think it is a complete sentence because 'whenever' = no matter when ) ...Families considered as the root of their happiness can strengthen them and make them become happy persons(I think poeple or individuals would be better). In addition, hobbies, sports and games can be serve(d) as a source (sources)of fun and enjoyment, these offer people lots of exciting moments.
Comparatively, some people see(consider or take) money as a source of happiness while other people define happiness as something deeper. It is clear that money is the(an) important thing(element would be better) in our lives, but some people are totally addicted to money. Except money, no other things (there is nothing else)can make them happy. Maybe some of them can get the happiness they want
ed , unfortunately most of these moneygrubbers are(were) unhappy and died alone. By contrast, some people define happiness as giving and they come alive by helping other people. They need to feel that they are doing something useful with their lives and other people, (and)concentrating on giving and helping can afford them this feeling and also(and so/thus) help themselves achieve happiness.
Moreover, some people get a sense of achievement from their work, and others find happiness in bringing up their children. I am sure(convinced, 'sure' sounds colloquial ) that
the people who hold their happiness are fortunate, no matter what kind of the happiness (it)is. Finally, what is happiness? I still do not find the answer, but I can say(believe. still, 'I can say is colloquial') when you feel happy, happiness is just around the corner.
I only correct some grammatical errors. Hope it helps.
This is a difficult topic for me too. But I recommend you to pay more attention to grammar first.
Besides, I suggest you aviod repeating the same word two much. For example, 'people' can be replaced by individuals, human, some people or some(I do not think person is proper here); and 'define' can be repalced by consider, take...as..., believe...as.
The reason you feel unatural could possibly because you use too much oral English in writing, and reading more nice essays and keeping on practising may help a lot.