假設你是李華，你的朋友Jenny向你詢問如何保持健康．請你給她發一個郵件提些建議．內容要點如下：
1．注意保持均衡飲食（keep a balanced diet）．多吃魚、肉、豆類等．
2．注意鍛煉身體，多參加體育活動．
3．保證充足的睡眠，不要熬夜，每天至少睡8個小時．
注意：
1．詞數：100左右；
2．可適當增加細節，以使行文連貫；
3．郵件的開頭已為你寫好．
Dear Jenny，
How nice to hear from you!In your letter you asked me how to keep healthy．

I would like to give you some advice．
As we know，you teenagers grow very fast，so you need to keep a balanced diet．You should eat more fish，meat，and beans，especially fresh vegetables and fruits．You'd better not eat too much sweet．Also，you should take physical exercise regularly instead of studying in the classroom all the time．For example，you can play basketball or swim after school．What's more，having enough sleep is very important．So I advise you to have at least eight hours of sleep every day and not to stay up too late．
Only in this way can you keep fit．

I would like to give you some advice．
As we know，you teenagers grow very fast，so you need to keep a balanced diet．You should eat more fish，meat，and beans，especially fresh vegetables and fruits．You'd better not eat too much sweet．Also，you should take physical exercise regularly instead of studying in the classroom all the time．For example，you can play basketball or swim after school．What's more，having enough sleep is very important．So I advise you to have at least eight hours of sleep every day and not to stay up too late．
Only in this way can you keep fit．

Yours，
Li Hua．