Calmness is the mental state of being free from agitation, excitement, or disturbance. It also refers being in a state of serenity, tranquility, or peace. Calmness can most easily occur for the average person during a state of relaxation, but it can also be found during much more alert and aware states. Some people find that focusing the mind on something external, or even internal, such as the breathing, can itself be very calming.
Calmness is a quality that can be cultivated and increased with practice. It usually takes a trained mind to stay calm in the face of a great deal of different stimulation, and possible distractions, especially emotional ones. The negative emotions are the greatest challenge to someone who is attempting to cultivate a calm mind. Some disciplines that promote and develop calmness are prayer, yoga, relaxation training, breath training, and meditation. Jon Kabat-Zinn states that “Concentration is a cornerstone of mindfulness practice. Your mindfulness will only be as robust as the capacity of your mind to be calm and stable. Without calmness, the mirror of mindfulness will have an agitated and choppy surface and will not be able to reflect things with any accuracy.” 
Another term usually associated with calmness is "Peace". A mind that is at peace or calm will cause the brain to produce "good" hormones, which in turn give the person a stable emotional state and promote good health in every area of life, including marriage. Seeing the rise in crime and diseases around the world which are more often than not the consequences of the emotions going 'out-of-control', it is therefore considered beneficial for many to stay calm and cultivate it in every possible situation, especially during stressful events such as demise of a family member or failure in business.
The term comes from Middle English calme, from Old French, from Old Italian calmo, from Late Latin cauma, "heat of the day", the "resting place in the heat of the day", from Greek kauma, burning heat, from kaiein, to burn, from Middle English calme, from Italian calma, from Vulgar Latin calma, from Late Latin.
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