Happiness is the most common word in the english language, people perceive it in many different ways and everyone has different thoughts about it.
Most of the time happiness is related to your life and your purpose. If you are able to live your life with the purpose you always wanted you can be the happiest person in the world.
The good news is that its YOU who can choose your life's purpose. What if one purpose is not achieved, se your goals further ad expand your possiblities and you can stay happy forever.