Exercise increases muscle mass. Regular exercise reduces resting heart rate. People should exercise because it makes them feel better. Those who exercise regularly can increase their life span.
I gave my students this multiple choice question: The following statements are from an article in a fitness magazine. Which of these is an opinion?

Only one answer is correct among these 4 choices:
- Exercise increases muscle mass.
- Regular exercise reduces resting heart rate.
- People should exercise because it makes them feel better.
- Those who exercise regularly can increase their life span.

Could you tell me which one is correct?

People should exercise because it makes them feel better.