Buddhi-yukto jahatiha ubhe sukrta-duskrte
tasmad yogaya yujyasva yogah karmasu kausalam
The Bhagavadgita 2:50-51
Yoga is skill in action. It is the act of yoking to reality, an active engagement to the perception of reality. I have come across several variants of this precept, sometimes in surprising places and sources that are unlikely to have exposure to the motivation for these verses. The skilled practioner of a craft is actively engaging in a gauging or reading of a facet of reality, and in doing so has a brief albeit unadulterated perception of his/her relationship with his/her immediate reality. This state may be described as zen by the mahayana buddhists, dhyana in hinduism, or as being in the zone by an athlete.