People believed for a long time that the heart was the center of a person's emotions. That is why the word heart is used in so many expressions about emotional situations.
One such expression is to lose your heart to someone. When that happens, you have fallen in love. But if the person who won your heart does not love you, then you are sure to have a broken heart. In your pain and sadness, you may decide that the person you loved is hard-hearted, and in fact, has a heart of stone.
You may decide to pour out your heart to a friend. Telling someone about your personal problems can often make you feel better.
If your friend does not seem to understand how painful your broken heart is, you may ask her to have a heart. You are asking your friend to show some sympathy for your situation. Your friend "has her heart in the right place" if she says she is sorry, and shows great concern for how you feel.
Your friend may, however, warn you not to wear your heart on your sleeve. In other words, do not let everyone see how lovesick you are. When your heart is on your sleeve you are showing your deepest emotions.
If your friend says, my heart bleeds for you, she means the opposite. She is a cold-hearted person who does not really care about your situation.
In the ever-popular motion picture, "The Wizard of Oz," the Tin Man seeks a heart. He wanted to feel the emotion of love, and was seeking help from the powerful Wizard of Oz to find a heart.
The cowardly lion, in the same movie, did have a heart. But he lacked courage and wanted to ask the Wizard of Oz to give him some. You could say that the cowardly lion was chicken-hearted. That is another way of describing someone who is not very brave. A chicken is not noted for its bravery. Thus, someone who is chicken-hearted does not have much courage.
When you are frightened or concerned, your heart is in your mouth. You might say, for example, that your heart was in your mouth when you asked a bank to lend you some money to pay for a new house.
If that bank says no to you, do not lose heart. Be strong-hearted. Sit down with the banker and have a heart to heart talk. Be open and honest about your situation. The bank may have a change of heart. It may agree to lend you the money. Then you could stop worrying and put your heart at rest.