I have never understood what does the exercise involve? Can you please tell me what is it that you "do" in those five minutes that you meditate? I want to try this. Thanks.
http://www.audiodharma.org/series/1/talk/1762/ is a good, free introduction (this is from a Buddhist center, but the podcast applies to mindfulness in general).
It's not the end-all-be-all book for meditation (or Buddhism) but it is a good starting place I think.
http://www.amazon.com/Beginners-Guide-Zen-Buddhism/dp/060980...