Life Without Guarantees

My question is a simple one, but in a way, one of the big ones. How do you live life when it has no guarantees? How do you dare to love someone, when they may die, or you may die? How do you dare feel safe walking in the world when maybe nothing will come in the next part, after death? These questions have never concerned me before, but suddenly I find myself thinking about them very much. I’m in my thirties but feel about 5 years old when I think this way, and almost wish I was, as at least I was oblivious to doubt then.
I know there can’t be guarantees of anything, but that thought is haunting me at the moment. Any of your thoughts would be very welcome.