know where (one) is going

To have a clear knowledge of what one wants to be or achieve and the resolute determination to make it happen. Since she was a little girl, she knew where she was going—nothing was going to stop her from being a fighter pilot. I wish he would pick a degree program and stick with it. I'm just worried that he doesn't seem to know where he's going in life.

know where you’re ˈgoing

know clearly what you want to achieve (in life, in your job, etc.): He knows exactly where he’s going. He wants to be an actor.