When I first started to journal, my writing was more about events that happened in my day. There was not really any substance to it and was more like a play by play of my day. I also had to force myself to write at least a paragraph per day. But I noticed as I continued to do it, my writing gained more and more substance and began to be more than just events. It became a way to release stuff from my brain, a way to sort things out and a way to communicate to my T things that I was not able to speak out loud (which in the beginning was everything).

I would say just start with what you did during the day if you are still struggling. The rest will come.