You're not alone in finding it challenging to figure out what you want to do with your life. From the time I was a teenager, I didn't know what I wanted to be when I grew up. I always found it difficult to plan my life at certain stages. There are things you can't plan like what it's going to be like when you go through a certain developmental stage in life. You just can't imagine what it's going to be like for you. I can say now what my passion is and how I want to spend certain phases of my life. But I didn't know until I went through a bunch of stuff.
Can you make a smaller goal, like what you want to do in the next year? Two years? Five years? Keep it small. Or maybe just pick a TOP THREE. The top three things I want in my life: for example, healthy habits, to maintain relationships with my family, and to have good character (to behave with integrity, to be honest, etc).
I don't think it has to be a job oriented goal like "to be a fireman" or "to write a book"! It can be about other things that give your life meaning and quality.
Just some thoughts. Hope that helps.