What is happiness all about?

I have been thinking about this for sometime now. What makes me happy...or for that matter...what makes anyone happy? I came up with a number of reasons for a person to be happy. But for each one I came up with an exception. I have tried to list them down below:
A person feels happy when
1. He has what he wants.
Example : A person might want a new car. He buys it and he is extremely happy for a week or so.
Contradiction : He would invariable come up with some other luxury which would be a necessity according to him and would be unhappy until hes able to buy it. This is a vicious circle and it revolves around money. Money enables people to buy whatever they want and this makes them happy. When they realize they do not have enough money they are unhappy.
2. He lives with ppl who he loves.
Example : I live with my husband and he takes very good care of me and so I am happy
Contradiction : I love my parents and want them to stay with me. I would also be very happy if my sister and bro in law stay with me. I miss them sometimes and that makes me very unhappy.
3. He is satisfied at work.
Example : I feel very happy when I have a great day at work. I experience job satisfaction.
Contradiction : A bad day at work leaves me frustrated, angry and unhappy.
I came up with many such reasons for a person to be happy. I however, also came up with contradicitons to the same. I therefore came to a conclusion. I was wasting my energy focussing on what I are missing, and the key to happiness was in taking pleasure in what I have. Happiness according to me lies in achievement. I however realized that happiness is however not a happening; it's a state of mind. I can have everything in the world and still be miserable. Or I can have relatively little and feel unbounded joy. I think that happiness is all about appreciating and consciously enjoying what I already have.

I then knew how to attain happiness, yet I could not put it into practice. I slowly realized that I was so used to my present state of mind that I actually prefered to be comfortable and unhappy, rather than endure the discomfort of changing my thought process and be happy. Learning to be happy was just like learning a new skill like when I learnt perl at work. It requires effort, tolerance and practice in the beginning
There are some people who say that being unhappy drives them to do more and grow in that process. They believe that if they become content and satisfied with what they have they'll lose their motivation to achieve more.
I am not saying that I would get rid of my desire to learn and be content with what I know. Happiness does not drain our energy. It adds to our motivation and keeps our spirits high. The positive energy that happiness emanates is contagious. You could motivate others to be happy by always being cheerful and happy.
Some of my friends questioned me on the practicality of this theory. My answer would be that it is practical. Its all about accepting change and being prepared to feel uncomfortable for sometime before you become confortable happy for a lifetime.
I certainly an going to give this theory a try.