I find it interesting and a bit ironic when I think about how the two little words "what if" can be both harmful and beneficial. In our daily lives, if we constantly ask ourselves that question, we will become chronic worriers. "What if I loose my job?" or "What if he/she never speaks to me again?" The list can go on and on, taking on a life of its own, overwhelming us. We are tense and stressed, which wears on our health and our happiness. I try not to ask that question in my personal life.
My fiction is another story, pun intended. I've learned that those same two words can create tension and suspense in my writing, which is a good thing. What if the reader knows that the killer is hiding in the basement but the main character doesn't know? What if she is about to go down there? Or, what if the main character's next-door-neighbor is a voyeur, always secretly peeking in her windows? And, what if, while he's watching, he sees a man attack her and rushes to her rescue? So many "what ifs."
The words can even generate ideas for plots and characters. Stopping at the post office to mail a package might not inspire story ideas in and of itself; it's just one of the many errands that have to be done that day. But, what about the man in line behind me who is talking to himself? What's going on with him? And, all of a sudden, my mind asks the question: what if? What if he recently escaped from a mental institution? What if he killed someone and can't cope with what he's done? What if? And then: what's next?