Hanging around optimistic people can help you see the glass as half full rather than half empty.
If your friends have a pessimistic attitude toward life, you’ll tend to see things from their point of view.
It’s not necessary to dump your pessimistic friends; just add optimistic friends to balance out the doom and gloom.
Also, if a friend starts to go negative, smile and change the subject; or, offer a glass half full take on things.
Who knows, you just might help a friend feel a little better.