We can answer this by understanding what is meditation?
Meditation is a mind that concentrates on a virtuous object, and that is the main cause of mental peace.
The practice of meditation is a method for acquainting our mind with virtue; the more familiar our mind is with virtue, the calmer and more peaceful it becomes. When our mind is peaceful, we are free from worries and mental discomfort, and we experience true happiness.
If we train our mind to become peaceful we shall be happy all the time, even in the most adverse conditions; but if our mind is not peaceful, then even if we have the most pleasant external conditions we shall not be happy.
Therefore, it is important to train our mind through meditation.