The following are examples of Zen machismo:

Comfort is an illusion:
I think the USMC uses this one as a littany against the disabling dread of hard work, meaning that comfort is fleeting and should thus not affect the mindset of the marine. Eventually the marine is expected to repeat this to himself at necessary intervals to get the job done.

My body is a piece of shit:
This one is attributed to a character in Robert Twigger's excellent book Angry white pyjamas. Another popular version of this quote was found in the movie Fight Club and the book as well I guess though I have not read it, when the unnamed narrator loses a tooth, Tyler Durden remarks that "Even the Mona Lisa is falling apart".

There are hundreds of examples of zen machismo in the Hagakure and in the innumerable stories of almost super human samurai who maintained granite like stoicism in the face of all kinds of stresses. Zen machismo seems like a product of a warrior ethos.

General machismo seems to be concerned with frivolous pursuits like getting the girl, showing up your friends, west-side-story style choreographed knife fights over parking lots and generally trying to ineffectually assert your manhood in situations where you feel threatened or insecure.

Zen machismo seems to have much more to do with real life or death situations, I guess you would be forgiven for acting a little cocky and confident if you were facing an army of Samurai the next day. Heck it might even boost morale.