It is impossible to remain calm in any situation. Also, we do not have to always be calm.
Nature develops us by constantly growing our ego. If we look at eons of human development, we can see development from basic survival desires for food, sex, family and shelter—desires we had as cave dwellers—through the egoistic desires that appear when we develop as civilizations: money, honor, control and knowledge.
The more the ego grows, the less calm we become.
Aggravation, agitation and stress are all states that nature urges us to feel in order to reach the recognition of our human ego as the cause of the turbulence, and by doing so, develop a sincere new desire to rise above the ego.
At this juncture, we need a supportive environment where we feel encouragement and confidence in order to rise above the ego.
One aspect of such an environment is regular learning and activity aimed at elevating us above the human ego, which shields us against any aggravations that come to unbalance us.
In other words, by regularly calibrating ourselves in order to recognize the ego as the source of our imbalance with our surroundings, and to rise above the ego, we would need to strengthen our supportive environment, which would in turn help us through any states we experience faster than if we were left to our own devices.