I'd like to be my own boss but starting a company of my own means I need to have good ideas. And I don't have a damn clue what I want to do in life

What do you enjoy, what would make it better or what needs continued maintenance to keep it working?
Start there, see if you can come up with anything.

I wouldn't know where to begin either if I wanted to start something

In today's world, almost any type of service business should work out well.
Whether it be as simple as interior house painting or small office cleaning, or small hauling. Of course if you wanted something less physical, why not open a photography studio. Weddings, graduations, etc., always seem to do well also.