So often as we move through our lives we are quick to place blame for our suffering and credit for our happiness on external factors. If only I had more money I would be happier. If only I had more power in my job or my family I would be happier. If only he or she treated me better and loved me for who I am I would be happier. We quickly come to find out that when we acquire more money, more power, and even more love we do not reach the level of happiness that we once thought that we would. Why is this? Happiness and suffering are not generated through the external world and material factors. They are a mindset that each and every one of us choose to create.
In general, people tend to identify the nature of happiness and suffering with afflictive emotions such as attachment, desire, aversion and ignorance. However, when we desire to be rich for example, and then we reach that level where we see ourselves as being rich the feeling of happiness that is experienced does not come without feelings of anxiety and worry attached. This is not pure happiness. This is the case with many of the things that we think will bring us happiness. In addition, as time goes on we start to lose the excitement and happiness that we once felt for the money, the power, or the fame. A pure source of happiness increases your satisfaction and joy more as you use it more.
The secret to true happiness is to let go of the mental afflictions that create suffering, even though from the surface they may seem like sources of happiness. Only once you are able to free the mind of these feelings of anger, greed, attachment, self-centeredness, desire, etc. then will you be on the path to true happiness. Fill your thoughts with love, compassion and altruism and remove the unwholesome state of mind. Though much easier said than done, training the mind to do this will bring you greater happiness and satisfaction.
For more on this topic, I suggest reading the book Reducing Suffering by Geshe Ngawang Phende and translated by Taryn Sue. It is an incredible resource on the study and practice of Buddhist Psychology.