"Pursuit of happiness" is a cliche used often by people who think that if have a wife I will be happy, if I have college degree I will be happy, if I have..... I will be happy.
This is all illusion. It is another story that this is how most people live in today's society which is purely materialistic.
The truth is: Happiness is a state of mind, not dependent upon externals. Just as you get depressed, excited, sad, greedy, loving and so on, you can develop the attitude of being happy regardless of what you have or don't have.
The traditional way of developing it is training to be grateful for what I have, contemplating that I am so much fortunate compared with a lot of people who lack what I have, learning to keep the cravings away, and leading a pure and simple life without pretensions.
Our needs are really very simple and limited. When we allow ourselves to think that we have much more than what we need, a sense of satisfaction develops and creates the state of happiness. Contentment is the key for lasting happiness.