What’s your biggest fear?

So the other day I was walking down the street with a new(ish) friend of mine and found out he has an extreme phobia of birds. When he was younger, he was attacked by a bird so it’s a pretty logical triggering reason. He’s tried therapy, yoga and a number of other tactics but can’t seem to conquer the fear. It got me thinking about my biggest fear. While mine isn’t nearly as extreme, public speaking was my biggest fear but I’ve recently overcame the fear by practicing and forcing myself into more situations that would make me speak in public more often. Whether it’s a small fear or serious phobia, what’s you biggest fear?