This is one of the most powerful questions, when asked about the right things. It is also one of the most annoying questions when wielded by curious preschoolers, but that's another story.
When we ask far-out questions, we really begin to use our imaginations. What if you just got a million dollars? Easily we can dismiss that question, knowing that it will never happen. Or will it? Even if it doesn't happen, we can be stretched by considering the possibility.
Everybody's favorite "what ifs" are different. What if she says yes? What if I get the promotion? What if I had the perfect day? What if terrorists came to Christ? What if Jesus gave me the opportunity of a lifetime...what would it look like? What if I actually enjoyed school? What if I tried to make my marriage work? What if I could kick this habit?
God can take our imaginations and lead us to greater service for him.