What is it? Since so many search in vain for happiness perhaps a proper definition is in order.
Before I begin to set out my thoughts on the subject, be aware that I'm no expert in the field, have no qualifications and am simply an old man.
In my humble opinion most people confuse pleasure with happiness. Things like drugs, alcohol, sex, video games, movies, fine food, money etc., etc., even love, are considered by many to bring them happiness. Some of those items taken in strength or combined, may even bring temporary euphoria. Indulging in such things one after the other or in some sort of rotation, may even prolong a perceived happiness for long periods of time. To me such things may bring temporary pleasure, and that's ok, but take them away or indeed over use them and the pleasure lessens or ends.
If we were to agree then, that these are temporary pleasures and not lasting or true happiness, we must find a true definition of happiness. I'll put forth this as a definition - peace of mind or, contentment if you prefer. I prefer peace of mind because, to me, it includes the mind, body and spirit. In addition, contentment seems temporary to me as you might feel after a satisfying meal. If we accept peace of mind as a definition, how do we all find our own peace of mind?
Thousands of books have been written on the subject and it might seem no one can agree on an answer. Perhaps that is because we are all unique individuals and approach the subject with our own prejudices. Still, some like me do find peace of mind. In my opinion therefore, there must be some basic elements that make up peace of mind. Before I set out what I think they are, I would caution not to dismiss them as they may seem too simple and, depending on where you are in your life, they may take a great deal of study. In fact, I study and practice them everyday - this is vital to success.
Before we begin, I advise this and advise reading it first thing every morning, "smile, you're on a grand adventure!" And if you hit any difficulties along the way say this, "This too shall pass".
I would advise to start with researching and developing a set of written ethics to live by, which are then read several times a day. I would start with ethics as they will be your compass. I would write them down because it forces you to refine and understand what each means to you. I would read them several times a day to ingrain them in your subconscious mind. That way, you will act and react to the outside world automatically, in the most appropriate manner. Here are the ethics I try and live by - I say try because I'm not perfect and occasionally fail:
The Golden Rule - do unto others as you would have them do unto you.
Strict honesty - do this everday in all your dealings
Don't criticise, complain or condemn - there are ways to instruct or put things right without them.
Remember the other person has their own story - understand other people
It's not about you - it's about the people you serve, their success is your success
Never argue - you can never win. You may win "the point" but you will lose friends and allies
Live frugally and healthy
Insist on excellence
Study human nature - we are vain creatures ruled by emotions. Everyone wants to feel important.
Know what you want - be as precise as you can
What you think you become - thoughts are powerful things.
Do at least one good deed every day - it makes you and the other person both happy
Work for the benefit of mankind - you'll improve your world and yourself.
Live debt free - a major boost to peace of mind. "Lying rides on debts back" - Franklin
Happiness comes from within - true by definition as peace of mind comes from within
Next, I would read and study the subject in depth. I would suggest reading autobiographies and biographies of successful people. They learned happiness the hard way and have a lot to teach.