Karma yoga resolves the false choice between action and liberation. One need not withdraw from the world to be free; one can act fully, but act as an offering, releasing claim to how the action lands.
The Bhagavad Gita is its foundational text. Arjuna faces a battle he does not want to fight; Krishna’s answer is not escape but the transformation of action itself.
“Your right is to action alone; never to its fruits. Let not the fruits of action be your motive, nor let your attachment be to inaction.” — Bhagavad Gita 2.47
The practice is subtle. Externally, a karma yogi looks like anyone else doing their work. Internally, the grip on outcome has been let go. gandhi read the Gita as a manual for karma yoga in political life. Seva is karma yoga in community form.