Karma yoga is an ancient concept. The path of karma yoga is described in the Hindu sacred text, the Bhagavad Gita. It is also taught by zen teachers.
The intention when practicing karma yoga is to give selflessly for the good of others without thought of one's self or attachment to the results of one's actions. Acting in this way is considered the right way to approach service and it is said to purify the mind.
Karma yoga is relevant to all yogis because, to some extent, everyone must undertake some actions during their lifetime. By practicing karma yoga, all of these actions, even the most mundane, can become part of one's spiritual path. Practicing karma yoga also means to fully accept one's dharma, or life’s duty, and to let go of selfish desires. In doing so, one sublimates the ego.
Volunteering one’s time and effort is often used as an example of karma yoga, but, actually, all of the actions one undertakes can be karma yoga. It is considered the attitude to the action, rather than the action itself, which makes something karma yoga. This means acting with the right motives, in the right way, to the best of one's ability, but surrendering attachment to the outcome. Some teachings recommend using chanting and mantras before and during the actions in order to develop the right mindset and approach to giving selflessly during one's service.