Your Dream

It is probably your aspiration to have some control in the movie business, if you've come out here to pursue it. Most have an all or nothing mentality, which is pretty much how you either succeed big or fail big. But failure should not be your fear. If you never tried, you already failed. But if you're "in the game" long enough, small things lead to big things. Having a good attitude whilst pursuing your goal is essential, though not required.
Part of pursuing this dream is also handling rejection.
Rejection is tough. You really have to switch your mind into this thinking that none of it is personal (much like dating). They don't want you in their project for a myriad of reasons, and frankly, most of them are dumb. OR, they don't like your script for some reason and offer dumb suggestions. OR they don't like your previous films and think the execution isn't for them. Again, the strangest reasons and everyone will casually lie to you to keep you on their radar. Again, William Goldman "no one knows."
His commentary track on "Harper" is perhaps the most honest take on the movie industry. From someone as successful as him, one should listen.

So none of this is relevant if you have "fuck you" money. I don't have "fuck you" money, but I do have "I don't need you" money. This type of money doesn't rely on being accepted by them, but it definitely has limitations. "I don't need you" money is essentially telling people you don't want to keep beating your head against a wall.

But for those with a dream...and most of these are pretty vague ("I want to be an actor" "I want to direct" "I want to write") I would say start looking it as work. I mean real work. Work that (if you're truly passionate about requires the thickest of skins). No amount of discouragement, though remain smart about your moves. Most people who are navigating this trench aren't going about it the way I would recommend. But there is no path to dodge land mines. So there's that as well.

I would say, in terms of dreams...or more accurately, passion... be VERY serious about it. I know a few people who frivolously go about it. Study. Study. STUDY! People you admire. They have insight. Forget the personal stuff, like you see on "Entertainment Tonight." Learn to listen closely, and be very serious about your work. But that doesn't mean being a serious person. It just means tapping into the core of why you are doing it. The residual effect of super serious people are un-fun productions (not that it has to be fun, but...it's grueling). Most people are scared about this, and grow defensive, because the issue is...if you care about something...it will hurt you. Allow it to. Admit that it does. Too many of you out there thinking having a thick hard exterior makes you a strong person. It makes you look dumb and everyone can see it.
The work is most important. Over anything else. It is what is etched in film. And will follow you.
So it better be something you care about.