Seek Friends Who Challenge You

The Talmud tells the story of Rebbi Yochanan, a great scholar who had a study partner named Reish Lakish. (Before becoming a rabbi, Reish Lakish was a bandit. But that's another story...) These two men studied together for many years, until one day Reish Lakish got sick and died. Rebbe Yochanan was seen walking in the street, totally depressed. His students asked him, "What's wrong?" He said, "My study partner died and now I have none." They told him, "Don't worry Rebbi, we'll take care of it." So they went and found a brilliant young man to study with Rebbe Yochanan.
Two weeks later, Rebbi Yochanan is seen walking in the street again, totally depressed. They asked: "Rebbi, what happened? Why are you so sad? We sent you the most brilliant study partner. What's the problem?"
He told them: "My new study partner is so brilliant that whatever I say, he brings 24 proofs that I'm correct. But when I studied with Reish Lakish, he showed me 24 proofs that I was wrong. That's what I miss. I don't want someone who will just agree with me; I want a partner who will challenge my position. In this way we will arrive at the truth together."
A good challenge - is that what friends are for? YES! The Sages say: "Better the criticism of a friend, than the kiss of an enemy." Your friend will tell you when you have spinach stuck in your teeth; your enemy will smirk and say you look great! The Torah speaks of Dikduk Chaverim, which literally means fine-tuning with friends. With this attitude, I see others not as adversaries, but as a welcome counterbalance to my own perspective. In choosing my friends, I want someone who will challenge me to become better in life, not just better on the tennis court.
Moral stories can improve your moral values.