Forcing is not good at all. Like, ever. If nothing is coming, start writing down what your body is experiencing – maybe you're sleepy or restless or you really need to wash your hair. And before you know it, all sorts of things start pouring out. Good luck!
I write about just that, "nothing". Sometimes, writing about nothing makes me realize even if it seems like I feel nothing, have nothing to write, nothing on my mind, etc. It turns out that even nothing is a something.
I dont put my thought into my journal. I just write, about anything that happened that day, and then it just sort of flows, I always go over my journals too. And I'll add, or change some wording depending. So sometimes when I'm just blah, I'll review old ones, and from that, it makes me self reflect and I'll write that down!