A Question as Old as Time...

So, here is a question as old as time: What derails your day most? So many of us wake up and are ready to go with our brilliant plan... only to find ourselves at the end of the day trying to finish something completely different than what we started out to do. Some say it is our creativity taking over and once we are on a roll, time ceases to exist. Others feel that if we were more structured, then things would go smoother and our original plans could move ahead properly. Is there a balance between the two different viewpoints? What have you found to be a way to balance between your creative side and your serious, business side?