I think that you mean being able to control your emotions rather than turning the other cheek. If you got mad over trivial matters you would be simply petty. A professional does not let his emotions run away with him.
Turning the other cheek is an overused phrase. Many people are so "forgiving" because they have no opportunity to rip their enemies to shreds.
Imagine that your boss is a real asshole. (Most people do not have to imagine this, they know this from experience.) You would gladly speak your mind to him or, even better, punch him in the face or kick him in the butt. However, you will not do it, because you are afraid of losing your job. It takes a bit of courage to admit to yourself that you are angry, frustrated and anxious, that you feel exploited, humiliated and powerless. Moreover, a feeling of shame may appear, if you are too honest with yourself. So why not just "forgive" your boss, turn the other cheek and suffer nobly to boost your ego. You will feel better if you manage to convince yourself that your morals are higher than those of your boss.
And then you come back home and get mad at your wife because the soup is not warm enough.
Some people in certain situations are capable of forgiving others. For example, a wife forgives her husband for betraying her. She is furious at first and full of sorrow but she gets over it, because she really loves the guy and gives him the second chance. She also does it for the sake of their children. Or a mother can forgive her child, a troublesome teenager, who stole her jewellery to buy drugs.
However, love and forgiveness are not stupidity, irresponsibility or bullshitting yourself. A responsible mother will forgive her son, she will not throw him out of the house but she will make him get a treatment of his addiction. The wife will give her husband one more chance, if she wishes so, but she will not tolerate his love affairs over and over again. Love and kindness have their limits.