Adress
Date
Dear..(penfriend's name),
Lovely to hear from you. How are you? I’m so pleased to hear that  you are starting to care about staying fit. With my own experience I can help you suggest some ways to keep fit healthy for you.
First, you should start to count your calories. That you don't eat much doesn't mean you get low calories. Instead, make sure you balance your body's nutrients and eat the right amount of them. You should not fast or skip meals because it is not only bad for weight loss but also for your health.Don't forget to eat less junk food. The next significant point which affects good health is doing exercises.You should exercise regularly to keep your body healthy. You should also avoid sleeping too much because sleeping too much causes fatigue and mental illness. Lastly, keep your spirits happy and relaxed so you don't get stressed or upset. It is also a way to get in good shape and healthy.
I wish you always be healthy and have a beautiful body as you dream.
Don't forget to answer me and let me know your effect after practicing.
You should be fine.
Stay healthy,
 (myname)