Krishna explains how karma works both ways, like the key that can lock or unlock depending on what one wants to achieve during one’s lifetime. By judicious handling of karma, that is by converting it into detached action, one can attain chitta suddhi that becomes the springboard for liberation, pointed out Sri V. Abhiramasundaram in a discourse. Chitta suddhi is the inner purity when the mind and heart remain unsullied by the influence of the senses.
The Gita advises training oneself to control the senses that have a powerful sway. The sense objects constantly enter the mind through the senses and instigate the mind to indulge in satisfying the desires. For instance, one sees an object and may get drawn to it. The mind goes back to it often, and the desire to possess the object takes root. When desires are thwarted it turns into anger. When in the grip of anger, one gets deluded and the sense of right and wrong, good and bad, etc is lost. Desires cause disturbance in the mind and there is only restlessness and yearning. This is the pattern in the lives of the worldly minded keen on material pursuits. They think these to be of great value for them.
In contrast, a yogi who has controlled his senses looks at the objective world as one constituted of Maya. He lives in this world, no doubt, but his mind is trained to be unattached. His vision is directed to the Lord and the permanent since he knows the ephemeral value of worldly enjoyments. He aims to do his work well and with utmost sincerity and hence all his acts are done as a penance with no attachment. He is not affected by success or failure, having overcome anger, pride, ambition, etc. In this effort of cleansing the mind, it is left to each one to assess the level of purity attained.