Serenity is being present to inner peace.
Its not a freedom from storm but peace amidst the storm.
Calmness of mind or serenity is one of the most beautiful jewels of Wisdom. It is the result of long and patient effort in self control. Its presence is an indication of ripened experience and of a more than ordinary knowledge of the laws and operations of thoughts.
We all experience problems and mis-fortunes at different times in our life.
The graph of life is never stable. Many of our dreams or plans inevitably shatter despite our efforts invested in them. But the ability to cope up the set-backs with the right attitude and staying calm is a sign of mature and wise person.
One of the great masters possessing this quality of Serenity was the grate inventor THOMAS ALVA EDISON. When his factory burnt down on 9th December , 1914, he told his son "Go get your mother and all her friends. They'll never see a fire like this again". When his son objected, Edison told "It's all right. We've just got rid of a lot of rubbish." He told the reporter, Although I am 67, I'll start all over again tomorrow".
Don't let the behaviour of other destroy your inner peace - Dalai Lama.