Reflections from a non-prolific writer

The weirdest feeling I've ever had is when I want to be writing but have nothing to write.

Looking back over my personal records, since 2015, I've written one book every two years. It's not a reflection of the speed with which I draft/revise, but rather, I don't seem to get an idea I'm truly passionate about writing until a year or so has passed since the last book I wrote.

Maybe that's the natural outcome when most of my books are personal to me in some way - I only have something to say about my own experiences when enough time has passed for me to have new thoughts/experiences/reflections. Though I have a commercial sensibility, I can't seem to write books solely for a commercial purpose.

But yeah, it's a very strange feeling when I want to be writing but feel like my head is empty of ideas. T_T