Dear [Friend's Name],

I hope this letter finds you in good health and happiness. I wanted to take a moment to express my heartfelt gratitude to you for being such a wonderful friend to me. I am truly blessed to have you in my life, and I want you to know that you have made a significant impact on my life.
Your unwavering support and encouragement have been a source of inspiration to me. Your kind words and thoughtful gestures have lifted my spirits during difficult times. I will always remember how you stood by me through thick and thin and never gave up on me.
I appreciate your patience and understanding of my flaws and imperfections. Your acceptance of me for who I am has given me the courage to be myself and pursue my dreams. You have been instrumental in shaping my personality and helping me grow into a better person.
I am grateful for all the fun times we have shared together. The memories we have made will stay with me forever, and I look forward to creating many more in the future. You have added so much joy and laughter to my life, and I cannot thank you enough for that.
I also want to thank you for your generosity and kindness. You have always been there for me, and I feel blessed to have you in my life. Your selflessness and compassion towards others are truly admirable, and I have learned a lot from you.
In conclusion, I want you to know that you are an amazing friend, and I am grateful for all that you have done for me. I hope we will continue to be friends for many years to come, and I promise to always be there for you whenever you need me.
With lots of love and appreciation,
[Your Name]