Boys Will Be Boys?

I have spent much of the past two and a half years trying to figure out exactly what this phrase is supposed to mean. You would think that after growing up with four brothers that I would have somewhat of an idea. I have been discovering, however, that I really do not clearly have an understanding of what my expectations should be when it comes to Josiah and, soon to be, Jacob. Is what they are doing really something that I should not allow them to do, or is it just that it is something I would not do? Also, is this really something that I want to make into an issue. (Once I give the instruction, it needs to be obeyed, which means I need to enforce it.) At the heart of the matter too, is the question of whether I am focusing on where my son's heart is, or if I am just changing his behavior? But then there are also times when we have certain expectations just to make our home more peaceful and safe, do not go in the elevator until mommy or daddy are in there, do not scream in the house, etc. Anyways, these are questions I have been facing regularly, especially this past week. I had quite an amusing time this afternoon watching Josiah play. Here is how it played out:
He brought all his little safari animals out of his room. He began lining them up on the arm of one of the chairs as he sang a marching song (one that he made up as he went along). It was a very peaceful activity. Next, he began to hit one at a time off of the arm of the chair onto the seat, making sound effects as he went. Suddenly he had a great thought. He went into our room and came back with one of my hair rubber bands. Once again he began to put animals on the chair. This time they went on one at a time and he would attempt to shoot them off with the rubber band. He tried this game for a little while, then grew tired of it and began tossing one animal at a time over the chair. Once all the animals were on the floor, he looked over at me. I let him know they would need to be picked up before he played with something else (Jacob would love to get his hands, and then mouth, on one of them). Josiah picked them all up, put them back on the chair, and then began to toss them a little further over the chair. This went on three more times, until he was throwing them with all his might, across the room against the window (along with some terrific sound effects). Really a harmless activity and great fun for Josiah. (I have to admit it ended up feeling a bit much for me.) Now, when pretty much any activity grows and escalates into endless possibilities, there are many times where I need to intercept, and this goes back to my many questions mentioned earlier. Josiah and I have great fun, but I almost always end up worn out!