What really works to make sustainable changes in diet and lifestyle? It's probably not what you think.(29)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 evenbetter,and quickly.(30)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 reason for 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,(31)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 vessel 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.
听前预测 预览四道题各选项，由Joy，willpower，exercise，wrinkles，quit smoking可以推测，短文内容与情绪和身体健康之间的关系有关。
29.Which are the keys to sustainable changes in diet and lifestyle?