The Martial Way, from Nigel Davies
I'm in the midst of reading Living the Martial Way: A Manual for the Way a Modern Warrior Should Think by Forrest E. Morgan. It's given me new respect for the warrior classes and provides a model for both traders and chessplayers. Of course we don't face any risk to our lives, but the discipline and thinking needed for life and death combat can be transfered to our modest pursuits.