I pretty much grew up in the Marines, and I always used to make the mistake of asking why whenever I got a crappy job. I guess I figured I could do it better, or at least be a little more motivated if I knew why I was doing something.
The answer I always got was “suck it up, eyes to the front and keep marching”. I took this to mean that they didn’t know why we were doing something, they only knew that we must do it.
It’s kind of the same whenever one asks the hard questions. Why do I exist? What purpose is there? Why should I act morally when so many do not? I mean knowing these things would help us live a little better, or at least motivate us a little to do so, right?
Well if one asks the clergy these questions, they might get the answer that one must have faith. Ask philosophers and they might say that one must become enlightened. Ask a scientist and they might get that science cannot yet answer all of these questions.
In other words, we do not know why we must do things, we only know that we must. In other words, “suck it up eyes to the front, keep marching”.