Many years ago, before martial arts classes we would kneel with our hands on our knees, backs straight, close our eyes and just work at stilling the mind for a while. Most of the time I can clear the mind anytime I need to now - it's really very helpful. It takes practice but eventually you figure out how to do it, and then you can sit a few more moments and decide what it is that is most important and demands your attention the most, and focus on that.