What Makes a Happy Life?

In Unit 7 "An Era for LOHAS," there is an interesting question for discussion: 

   "In Chinese, the literal translation of LOHAS means "happy life."  How do you   define a happy life?  What are its essential elements?"

This morning, after discussing the 2nd mock exam, I asked Class 314 this question.  The following are their answers:

1. Laughter

2. Mental and physical health

3. Eternal youth

4. Contentment

5. Achievement

6. To love and to be loved

All these are answers I had expected to hear from them except for #3 "eternal youth."  I hadn't expected anyone their age would ever regard eternal youth as an important element of a happy life, because they are so young, ages 17 to 18.