Now, that is a writing prompt!
I am 62 years old, and life is still mostly mysterious to me, if, by "mysterious," we mean unpredictable and inexplicable. It would be dreadful to me if it were not thus, because that would imply utter predictability. There might be some that would like to know what is going to happen to them for the rest of their lives, and certainly, I do like knowing the sun will rise tomorrow and my grass will grow. But for me, the mystery is what makes life worth living. Life is meant to be an adventure, a journey to new places.
This subject raises some interesting questions about issues like pre-determinism and free will. For those who believe in a divine "plan," is life more mysterious because a divine plan must be inherently unknowable? For those who are strict self-determinists, does that leach all the fun out of the journey, thinking that one makes choices that put one on a particular trajectory, with little in the way of surprise? My own experiences make me want to tend to straddle the line, knowing full well that some choices that should have led me logically to a particular place have not always done so, and also having experienced some sychronicities and serendipities that seem inexplicable without some plan in the universe.
There are, of course, those who are of a strictly scientific bent, who think that everything, including us, is a collection of atoms, driven by laws of science and nature. If that is the case, then the term "mysterious" takes on a different meaning, seeking to solve mysteries by learning those laws, but still mysterious.
Einstein(1949) managed to reconcile all of this, I think, saying,
The most beautiful and deepest experience a man can have is the sense of the mysterious. It is the underlying principle of religion as well as all serious endeavour in art and science. He who never had this experience seems to me, if not dead, then at least blind. To sense that behind anything that can be experienced there is a something that our mind cannot grasp and whose beauty and sublimity reaches us only indirectly and as a feeble reflection, this is religiousness. In this sense I am religious. To me it suffices to wonder at these secrets and to attempt humbly to grasp with my mind a mere image of the lofty structure of all that there is.
Having said all that, I also am aware that we have a human need to look back and try to take the mystery out of things, to impose a narrative on our lives that provides an explanation for what we have done and what has happened to us, to make connections that give us cause and effect and a means of going forward more knowingly. But time after time, in spite of my having done this, going forward still remains a wonderful mystery.