假设你是李华，你的朋友Jenny向你询问如何保持健康．请你给她发一个邮件提些建议．内容要点如下：
1．注意保持均衡饮食（keep a balanced diet）．多吃鱼、肉、豆类等．
2．注意锻炼身体，多参加体育活动．
3．保证充足的睡眠，不要熬夜，每天至少睡8个小时．
注意：
1．词数：100左右；
2．可适当增加细节，以使行文连贯；
3．邮件的开头已为你写好．
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．