Coping with the fear of losing my parents - need advice, please

Assalamualaikum, does anyone else have this worry? I love my parents a lot and I'm so grateful for how they raised us. I try to be an obedient son and treat them kindly, doing what Allah and the Prophet (pbuh) guided us to do. They're in their early 60s now, and I feel anxious most of the time - like 80% of the time - thinking I might not see them tomorrow. I'm terrified of losing them. I catch myself being extra careful and constantly anxious. When I see them smile, laugh, or joke, I immediately make dua for them and ask Allah to keep them with me. I can't imagine losing them; it would tear me apart. I remind myself it's all qadr from Allah and that they're in Allah's mercy. When their time comes, it will be a merciful meeting with their Lord, and that thought comforts me a bit. But the sadness is mostly for me. I can't picture coming home or going downstairs and not finding one of them. They're everything to me - my father is my heart and my mother is the breath of my life. I want this constant anxiety to stop. I want to enjoy those moments with them without being overwhelmed by fear. I read that the average age can be around 63 and that made me more worried. How do the truly patient, faithful Muslims (the nafs al-mutmainnah people) handle this? How do I deal with this feeling that hits me almost every time I look at them? Jazakum Allahu khairan for any advice, duas, or personal experiences. Please be gentle in your replies.