当然！以下是一篇简短的500字左右的英文信件正文，适合用于正式或半正式场合：

Dear [Recipient's Name],

I hope this letter finds you in great health and high spirits. It has been quite some time since we last connected, and I wanted to take a moment to express my gratitude for the support and encouragement you have consistently shown me over the years.

As you know, life can be both challenging and rewarding, and your guidance has always been invaluable. Whether it was through professional advice or personal insights, your words have often provided clarity during moments of uncertainty. For that, I am deeply thankful.

Recently, I have been reflecting on our conversations and how they have shaped my journey. Your ability to see potential where others might not is truly remarkable. It is inspiring to witness someone who believes in the power of perseverance and hard work. These qualities resonate with me greatly, and I strive to embody them in all aspects of my life.

In addition to expressing my appreciation, I also wanted to share a recent development. [Briefly mention any relevant updates or achievements, e.g., "I recently completed a project that I believe aligns with many of the principles we discussed."] This accomplishment would not have been possible without the foundation you helped build, and I am eager to continue growing and learning from your example.

Looking ahead, I am optimistic about the future and excited by the possibilities it holds. As we navigate new challenges together, I remain committed to maintaining the strong relationship we have cultivated. Please do not hesitate to reach out if there is anything further I can assist with or discuss.

Thank you once again for being such an incredible source of inspiration. Your friendship means more than words can convey, and I look forward to staying in touch.

Warm regards,

[Your Name]

这个版本既表达了感激之情，又提及了个人成就，并展望未来，非常适合用来维持长期联系或加深关系。