There is now ample scientific evidence that smoking is dangerous to health and that eating too much and exercising too little can lead to medical problems such as diabetes. Many people seek to adapt their behaviour in the light of this evidence. They try to stop smoking, or vow to go to the gym to exercise more and reduce the amount of sugary foods they eat. In many cases, people do not follow through on their promises and vows.

a. Are these examples of irrational behaviour?

b. How does the content of this chapter help you to explain why people do not carry through their plans to stop smoking or exercise more and live a healthier lifestyle?