[解析]
Dear Jack,
As we all know, stress is a natural part of everyday life, so I'm writting to tell you that you don't have to worry about it. You should know how to deal with stress.【高分句型一】Here is some advice for you.(点题)
First,believe in yourself.Be confident and have a good attitude when you have many difficult situations.【高分句型二】Second,learn to relax.The best way to relax is to take part in physical activities regularly ,which can help us stay in shape.Third,you can ask your parents or friends for help.Besides ,a healthy body can give us much energy to face the busy school life.(具体建议)
Yours,
Xiao Ming