Are all thought downloads negative?

I’m just curious. It seems that almost every thought that comes out of my brain onto a piece of paper is negative. Is that just how brains are? It’s worry and anxiety and catastrophic thought etc. if my brain just does what it wants. Is this what Brooke means when she says that brains are like unsupervised toddlers with knives? Mine is RUNNING the show and none of what it thinks, without my intentional intervention, is positive. Is that just how things are?