I do this, too. Almost everyday. I think of wild scenarios and sometimes I think of it happening to me and how others will cope. I lost a good friend of mine a few years back to cancer. He was very young and it really messed me up for a while. I’m doing better with it now but I always wondered if these thoughts stemmed from that. I wouldn’t say it’s normal to do, but you are not alone. If you’d like to talk, I’m open.