Answer and Explanation:
Dear...,
I just heard the good news! Congratulations! I know how hard you studied for this exam over the past months. You really applied yourself, and now you are reaping the fruit of your sacrifices. This is a well-deserved moment of success.
I just wanted to say I look up to you and hope to develop your discipline and sense of purpose someday. When you decide to do something, you will move mountains to achieve it. It requires a lot of strength for someone to say no to the little temptations, to procrastination, and to laziness. And you are the strongest person I know.
Enjoy your success! Let's celebrate soon!
Yours,
...