Or is it stoic Zen?

I first learned of Stoicism in my last semester of college before entering the Marine Corps. It was a class in ancient philosophy. The timing was fortunate. Stoicism was the philosophy of Greek and Roman elites. Before entering public life men were required to serve in the phalanges and legions. This requirement was synonymous with public service. Stoicism gave them the mental strength to abandon the indulgence granted by their stations in life for the rigors of the military campaign. Marcus Aurelius, most famous of the Stoic philosophers, spent two thirds of his life as Emperor leading troops against Parthia and Germanic tribes.

It is no accident that Zen was the religion of the Samurai. Both Zen and Stoicism assert the primacy of one's mental state for happiness. Both deny the importance of external forces on internal sense of well-being. Both are keenly aware of the power of negative emotions to subvert mental harmony. Both hold that mental fortitude is more reliable and of greater value than physical luxury.

The zenist will speak of training to meditate. This may take the form of sitting, but it can also be in repetitive actions or even martial arts. Both eschew salvation and paradise for happiness. Both believe happiness is achieved through a trained, disciplined mind. The zenist will sat that the path is understanding the impermanence of all things. The stoic will say it is through reasoned conformance with Nature, but will also admit to the impermance of all things. Both will assert that happiness is achieved by letting of all impernanent things.