Excellent reply, Opher.
I try to remind myself that part of the "formation" process in meditation is the ability to recognise the distraction and to re-center. But never let this upset you - we will always have distractions.
The movement sugestion was good, too. depending on whether you are sitting on floor with - w/out pillow or on chair or walking meditation.
The use of a mantra (which can be anything) also helps focus your mind and breathing. Especially when starting out this helps you in the sense that you will know immediately when your mind has started to wander. But also, as you get more comfortable - or familiar with the process - the tangents this mantra takes you on will be useful, rather than distracting.
My default mantra has been: I am an olive tree growing in the house of G-d.