Well, no one said you must write a freaking saga. You can always write short novellas or even essays. Just something purely for yourself. I don't write much either.
My expectations for manga (or, well, anything really) are usually pretty low. Maybe it's due to a whole bunch of disappointments I've faced before, when I was younger. So I'm used to taking things I like in my own hands, making them my own and making sure they are what I need them to be. With fiction, it's very easy since I can always go ahead and write, or at least come up with a few headcanons to complement canon.
I guess I really am a pretty cold person. I can only passionate about things that are under my control, and even then, I never let my passion get in the way of usual life.