To start the letter, you can greet your friend like this:
Dear Adrian,
Thank you for your email. I appreciate your interest in my activities. Regarding your questions, I don't participate in sports either. Instead, I enjoy daily walks in nature and practice yoga for fitness. As for the importance of sports, while they offer physical benefits, I believe it's essential for individuals to engage in activities they are passionate about. Pursuing painting and learning a foreign language brings me joy and holistic well-being. I hope you found my responses insightful.
Warm regards,
[Your Name]