Remember, other people's views and trouble can be contagious. Don't sabotage yourself by unwittingly adopting negative, unproductive attitudes through your associations with others.
If you encounter a downhearted friend or a colleague who has suffered a sudden reversal of fortune, be careful not to be overcome yourself by the apparent misfortune. Remember to discriminate between events themselves and your interpretations of them. Remind yourself: "What hurts this person is not the occurence itself, for another person might not feel oppressed by this situation at all. What is hurting this person is the response he or she has uncritically adopted."
It is not a demonstration of kindness or friendship to the people we care about to join them in indulging in wrongheaded, negative feelings. We do a better service to ourselves and others by remaining detached and avoiding melodramatic reactions.
Still, if you find yourself in conversation with someone who is depressed, hurt, or frustrated, show them kindness and and give them a sympathetic ear; just don't allow yourself to be pulled down too.