[originaltext]What really works to make sustainable changes in diet and lifesty

What really works to make sustainable changes in diet and lifestyle? It’s probably not what you think. Years of clinical research proves that the real keys are pleasure, joy and freedom, not willpower and hardship. Joy of living is sustainable; fear of dying is not. Why? Because life is to be enjoyed. There’s no point in giving up something you enjoy unless you get something back that’s even better, and quickly. When people eat more healthfully, exercise, quit smoking, manage stress better, and love more, they find that they feel so much better. So quickly, it reconstructs the reasonfor making these changes from fear of dying to joy of living. Fortunately, the latest studies show how powerful the mechanisms that control our health and well-being are. When you exercise and eat right, your brain receives more blood flow and oxygen, so you become smarter, think more clearly, have more energy, and need less sleep. Your face receives more blood flow, so your skin glows more and wrinkles less. You look younger and more attractive. In contrast, an unhealthy diet, lasting emotional stress and smoking reduce blood flow to your face so you age more quickly. Smoking accelerates aging because nicotine causes your blood vessels to become  narrower, which decreases blood flow to your face and makes it wrinkle prematurely. This is why smokers look years older than they really are. One of the most interesting findings was that the mothers’ perception of stress was more important than was objectively occurring in their lives .In other words, if you feel stressed, you are stressed.
Questions 19 to 22 are based on the passage you have just heard.
19. Which are the keys to sustainable changesin diet and lifestyle?
20. Which of the following practices can make people feel better?
21. What’s the benefit of exercising and eating right according to the passage?
22. What conclusion can we draw from the passage?