How to write a thank-you card in English?

Dear [Name],

I hope this card finds you in good health and high spirits. I wanted to take a moment to express my deepest gratitude for [specific reason you are thankful]. Your [kindness/generosity/support] has truly touched my heart, and I am incredibly grateful to have you in my life.

I am truly blessed to have such an amazing [friend/colleague/family member] like you. Your [thoughtfulness/helpfulness] has made a significant impact on my life, and I cannot thank you enough. It is rare to find someone as [kind/caring/selfless] as you, and I consider myself fortunate to have you in my corner.

Your [act of kindness/generosity] came at the perfect time, and it made a world of difference to me. Your [support/encouragement] has given me the strength and motivation to overcome the challenges I was facing. I am grateful for your unwavering belief in me and for always being there to lend a helping hand.

Please know that your [gesture/action] did not go unnoticed or unappreciated. It is gestures like yours that restore my faith in humanity and remind me of the goodness that exists in this world. Your [thoughtfulness/generosity] has inspired me to pay it forward and be a better person myself.

Once again, thank you from the bottom of my heart for everything you have done for me. Your [kindness/support] has touched my soul, and I am forever grateful. I look forward to continuing this incredible journey together and creating many more beautiful memories.

With heartfelt thanks,

[Your Name]