The following is a sample birthday letter for your close friend on their birthday and letting them know how much they mean to you in general.

Sample Birthday Letter To A Close Friend
June 1, 2020
Dear Jane,
Happy birthday friend! I want to wish you very warm congratulations on your special day and offer my best wishes for many, many more great birthdays to come in your future.
I hope this particular birthday is the best one ever for you. Knowing you, you probably have a list of exciting things planned to do this year in order to celebrate it with your wonderful family. Keep this in mind: while everybody grows old, not everyone grows up!
Sounds like me and you, right? Whenever I need to put a quick smile on my face, I just think about all the good times we’ve shared over the years. You look as young and beautiful as the first day I met you. Did you discover the ‘fountain of youth’?
Also, I want to thank you for being there for me this past year when I really needed help. But, that’s what friends are for, and you’re a good one. Please know that I will always be there for you too.
Here’s to wishing you a long, healthy, and prosperous life my friend!
Again, happy birthday.
Love,
Lisa