It is while we are in society that we are often confronted with disagreeable sights and sounds, etc., which tend to evoke harmful and unhealthy thoughts, and it is then that we need mindfulness to restrain ourselves from entertaining them. While we are at work, sense desire, ill-will, jealousy, pride and other unwholesome thoughts are sure to arise and upset our balance of mind. It is then that we need meditation to check such harmful elements. If we are not slaves to our passions, if we are strong-willed, we can restrain ourselves and curb the conflicts in us.
Control of the mind is the key to happiness. It is the king of virtues and the force behind all true achievement. It is owing to lack of control that various conflicts arise in man's mind. If he is to control them he must learn not to give free rein to his longings and inclinations and should try to live self-governed, pure and calm.
Calmness is not weakness. A calm attitude at all times shows a man of culture. It is not too hard for a man to be calm when things are favourable, but to be composed when things are wrong is hard indeed, and it is this difficult quality that is worth achieving; for by such calm and control he builds up strength of character.
Piyadassi Thera, The Buddha's Ancient Path