Being a filmmaker must be the most boring as well as the most exciting profession in the world.
Boring, because you've already seen the film you wish to make in your mind. That's like the greater spoiler crisis. In fact, the very fact that you already know everything about the film even before it's made makes your reality a downer. For what it's worth, the filmmaker takes the onus of making life interesting for the audience at least by persisting with what's in his head and working towards translating the mental picture into a physical reel.
Exciting, because the filmmaker gets to create an alternate reality; a world that is controlled by none other than him. He moves things around like a chess-master who is basically playing against himself as there are no opponents in the field of cinema. It's only you and the time. So many things can go against you. The sun may not shine when the camera wants it to. Anything can happen. And anything does happen on a movie set.
PS. During my interview of Ang Lee for Life of Pi (2012), i couldn't help but ask what inspired him to become a filmmaker. His reply was as enlightening as his aura: he has always been a curious person, looking for answers and he found out early in his life that you can't always get them too conveniently.