Here are some inspiring birthday messages for a friend:

1. "You’ve achieved a lot in very few years! But I believe that there’s still more to achieve. Keep soaring higher and higher, my friend."
2. "Set your goals high and your achievements even higher!"
3. "Your friendship is a treasure, and I’m grateful for it every day."
4. "Wishing you the happiest of birthdays! Your friendship is one of the greatest gifts life has given me."
5. "May this year bring forth amazing things for you. Happy birthday!" ^{1 2 3 4}.