I believe that happiness is a state of mind, not some tropical paradise that if we strive hard enough we can arrive and have a pina colada and dance topless while singing hallelujah with angels (or whatever the idea of paradise is these days..)
To me, happiness is being content. Happiness comes from the inside out. Someone can find their car keyed tomorrow morning. One person will spend the whole day cursing and worrying about it, thinking how to protect the car from being keyed, how much it's going to cost, how they would punish the perpetrator, how to catch them etc etc. Another person will see their car keyed and think "bah, no biggie - I'll fix it later this week.", write it down on their notebook and not worry about it again and spend the day doing whatever they do. The event was the same - it was what the two individuals did with it that generated hatred/contentment in each of them.
I don't like to think of happiness as a constant state of MDMA-like euphoria, in which you wear a wide grin on your face 24/7 and smile and laugh at everything. I feel it's more like a natural/neutral state, where nothing can shake you, move you out of course. Feeling in peace and at place wherever you are, and emanating contentment and having a presence which flows with the world, instead of swimming against the current. An acceptance of things, rather than a judgmental blocking. It is what Ira Byock describes as "dying well" in his book with the same title ("Dying Well: Peace and possibilities at the end of life"). We are all dying, from the moment we are born. That's the only thing for sure. Are you going to die well? Or are you going to try and hold on to your sense of identity and self, and all sorts of other things that don't really matter?
I like a Zen approach to happiness. I believe that if you are looking for happiness in other things (a car, relationship, promotion, moving to a more wealthy area, whatever) you will always be deluding yourself. It's like the parable with the dog and its tail. The dog represents humans and the dog's tail is happiness. If the dog tries to catch its tail it will run round and round and round, and never catch it. But if the dog walks straight, happiness follows.
Many people have a "scarcity" mentality with regards to happiness - "happiness is something rare, something few people have achieved, and if I want to have it I need to make more money, get a more beautiful partner, move out of here, quit my job etc. And I have to get to it before everyone else does." People are trying to keep as much of happiness as they can, lest it goes away. But it's like a performance of beautiful piece of music - if you try to hold on to it, you lose it. You just have to let go and experience of while it lasts.
I believe that to be happy you need to have an "abundance" mentality - a mentality of giving, not of taking. The universe is giving. When you realise happiness is not a commodity that can be bought and sold, but a state of mind that comes from within, you can share your happiness with others (not by making their happiness dependent on being around you so they can be happy, but by teaching them and sharing how they can attain that state of happiness from within themselves).
People like Mihaly Csikszentmihalyi (pronounced "chicks-sent-me-high-ee" - author of "Flow"), Ken Robinson ("The Element"), Patsy Rodenburg ("Presence"), all highlight the importance of finding the thing(s) that we are really passionate about, which matter to us the most, activities that make us lose track of time - and dedicate our lives in doing these things we do best in order to feel alive, present, "in the zone", experience what Csikszentmihalyi calls "state of flow".
I personally find meditation and Zen art and writings to be very demonstrative of this - the Tao Te Ching (
http://academic.brooklyn.cuny.edu/core9 ... te-v3.html - although I really like the Tolbert McCarroll translations most) is a classic, and Alan Watts' writings (
http://www.leary.ru/download/watts/Book ... %20Are.pdf) are simply beautiful to read or listen to. Eckhart Tolle's "The Power of Now" also offers some interesting points.
And I think a necessary (but not sufficient) condition to happiness (contentment) is honesty (e.g. Brad Blanton's "Radical Honesty"). Explicit honesty with everyone, about everything. Call your parents/sisters/syblings/children/partners, tell them you love them. Do they know? Of course they do. But when did they last hear it from you? Tell them why they matter, and call up people towards whom you are angry and tell them why. And be honest with yourself. And pay attention to the sensations in your body as you say these things.
What do you really want? Are you happy where you are right now? If you knew you were going to die in 7 days, would anything would have remained unsaid? Is there anything left incomplete? Would you die in peace (assuming there is no physical pain)?