Calm
Being calm is a skill that needs to be practiced and developed. Thick skin or a centred mind, whatever you want to call it.
By reacting we exacerbate the situation and make it worse. Sometimes, it is good to take a step back and evaluate whether it even merits a reaction.
We have limited bandwidth to deal with things. Atleast 80% of 'situations' can be resolved amicably and without much difficulty if we JUST STAY CALM.
Being non-confrontational is not a bad thing if it helps you resolve things and move ahead.