Learning not to be affected is an important step. If you were influenced by a situation, how can you change it? If 15 people are crying and you go there and join them in the crying, you're simply added one more miserable person; you have not done anything to benefit people. Instead, if you're really strong and can maintain your own equanimity, all 15 people will be benefited by your strength."
Don't give your power or peace of mind away. To anyone! Retain positivity and don't engage in negative conversation!