For me, serenity is something that could be found in a calm and easy situation, be it a walk in the forest or a view of the pebbles at a beach.
One could use different methods to calm down. Chances are that that there are as many methods as humans. Some prefer to listen to smoothing music with sounds of waves rolling in on a desolate shore. Others use physical activities, such as yoga. A third group looks at paintings and photos.