Suppose you had a bad cold during your last trip to a famous mountain. The tourist guide has helped you a lot. Write a letter of thanks to the travel agency. Your letter Should include:
1) a description of your case
2) thanks to the tourist guide and the travel agency
You should write approximately 100 words. Do not sign your own name at the end of the letter. Use "Wang Lin" instead.

A. Rich people know that health is wealth.
B. Exercise does not necessarily mean a big-money game.
C. Proper exercise is a must even if you are not overweight.
D. One will pay dearly for ignoring exercise due to the heavy demands of life
E. Old age or poor health is never an excuse for being inactive.
F. Exercise is good as long as it helps lose weight.
G. The right proportion of muscle and fat is the criterion of health.

A．self-control
B．self-analysis
C．self-protection
D．self-improvement