The purpose of meditation is to cultivate those states of mind that are conducive to peace and well-being, and to eradicate those that are not.
If we examine our life we will discover that most of our time and energy is devoted to mundane activities, such as seeking material and emotional security, enjoying sensory pleasures, or establishing a good reputation.
Although these things can make us happy for a short time, they are not able to provide the deep lasting contentment that we long for. Sooner or later our happiness turns into dissatisfaction, and we find ourselves engaged in the pursuit of more worldly pleasures.
Directly or indirectly, worldly pleasures cause us mental and physical suffering by stimulating attachment, jealousy, and frustration. Moreover, seeking to fulfill our own desires often bring us into conflict with others.
If true fulfillment cannot be found in worldly pleasures, then where can it be found? Happiness is a state of mind, therefore the real source of happiness lies in the mind, not in external circumstances.
If our mind is pure and peaceful we will be happy, regardless of our external conditions, but if it is impure and unpeaceful, we will never find happiness, no matter how much we try to change our external conditions.
The method to make our mind pure and peaceful is to train in meditation.
For more information on meditation see The New Meditation Handbook.