What worries me the most?

I'm worried when are my parents going to die, I've been told that I won't have them forever that at one point they'll be gone. But when will they be gone, I love both of my parents so much they make me happy when I'm sad, and I enjoy making them laugh. My parents have always been there for me protecting me and teaching me. My parents have taught me more about life then what a school teacher can teach me about anything. Sure sometimes they mortified but all big moments of my life have happened with them around, and I'm happy because of that. To advice to people anywhere be nice to your parents, try to help them, because at the end of everything you wished you thanked them for everything they did.