The purpose of meditation is to cultivate positive states of mind, conducive to peace and well-being, and overcome negative habits of mind.
If we examine our life we can see that most of our time and energy is devoted to seeking material and emotional security. 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.
Happiness is a state of mind, therefore the real source of happiness lies in the mind, not in external situations. If our mind is peaceful we will experience happiness, regardless of our external circumstances, but if it is unpeaceful we will never find happiness, no matter how successful we are in improving our external conditions. The method to make our mind peaceful is through meditation.