I began my martial arts training when I was eight years old. I studied Kenpo karate at first and as a part of this training, I was taught meditation, mantras, and kuji-in; in yogic terms mudras.
While mantras and meditation have been a part of my life, I had almost forgotten the practice of kuji-in until I started to learn the various mudras in yoga. I find it rather interesting how these types of practices dominate in the Eastern world.
To learn more about Kuji-in, here is a link to the Wikipedia article.