If your diploma is for a field that you are not passionate about, it doesn't matter. This is the United States of America. You can still, thank God, change your mind, reassess, modify, plan for your passion even now. Another important concept. You'll not reach your passion without it.
Planning requires an organized mind.
If you don't have one, you've got to go out and build yourself one, or hire yourself one. Without planning and an organized approach to whatever it is you want to do, you are going nowhere. But I have to go back to perseverance. Neither passion or planning will gain you much without it. Make certain you know the difference.