How do you write a letter to your younger brother scolding him for having neglected his health?

Dear [Brother's Name],

I hope this letter finds you well, but I'm really concerned about your health lately. It's important to take care of yourself, and neglecting your well-being can have serious consequences. Please make an effort to eat properly, get enough rest, and stay active. I care about you and want to see you happy and healthy.

Take care,
[Your Name]