The great Zen master, Hakuin Ekaku (1686-1768) said:
Meditation in the MIDST of activity is a billion times superior to meditation in stillness!
"The everyday mind is the training ground" by Onozawa Kankai
It was a philosophy that appealed to lay people, including the samurai, because it offered them an opportunity for salvation that many traditional schools of Buddhism had reserved to those who left the ordinary life and devoted themselves entirely to monastic practice.