[Your Address] [City]
Date: [Date]
Dear [Friend's Name],
CONGRATULATIONS! I jumped with joy when I heard that you [achievement, e.g. topped the board examination / won the state-level chess championship]. I told everyone at home, and they were as delighted as I was — though, honestly, none of us was surprised.
I have watched you work for this — the early mornings, the practice, the discipline when the rest of us were playing. Your success is not luck; it is well-earned, and no one deserves it more. You have made all of us proud and set a benchmark I will now use to push myself too.
This calls for a proper celebration. The treat, of course, is yours to give — I will settle for nothing less than [treat]!
Convey my respects to uncle and aunty; they must be over the moon. Wishing you even bigger successes ahead.
Your proud friend, [Your Name]