Karma yoga explained in 3 definitions :
The first one is SAMATVA BHAV, i.e., EVENNESS OF MIND. Having the same neutral, stoic attitude towards the result of an action whatever be the result. Our Raga Dvesa (likes & dislikes) are neutralized. This attitude is KARMYOG.
The second definition is KAUSHAL, i.e. DISCRETION IN ACTION. It means to use our discriminative intelligence, intellect to see whether the action is right. Buddhi (Intellect) will be different from one person to another– Kaushala – is our capacity to interpret things correctly. This capacity to interpret is discriminative intelligence. Then decisions are made according to what is right and what is wrong (Dharma & Adharma) and are not based on personal likes & dislikes or convenience.
The third definition is Dissociation from the Association of pain. It means tune away from the association with pain and move your attention to other things. Understanding that it is usually a simple non gratification of desire that causes pain.
Karma involves role-playing. Sometimes a particular action is to be done only because you are in that situation. Events occur because they have to. Once we understand this, then everything becomes meaningful. Let there be no attachment to action and let the results be received by us with Grace. In short, Our choice is only in performing the action never to the results thereof. Usually it is our response to the result of action that is the problem.