Karma is the Sanskrit word for action.  Because thought is an action, karma includes our thoughts and actions and their collective effect on us.  This is known in psychology as our conditioning.  Everything that is experienced, including thoughts, leaves a kind of mark on us, a fact now borne out by modern neuroscience. These experiences affect our future thoughts, impulses, and experiences. We can overcome the negative burden of this conditioning, our karma, by performing selfless action and ultimately by transcending our narrow, private personality so that all conditioning drops away.Karma yoga, the path of selfless action, is one of the four paths to self-realization described in the Bhagavad Gita. When self-realization is achieved the chain of causality is broken and our conditioning no longer controls us. This is accomplished through life-long selfless service and the practice of detached action. Gandhi is a wonderful example of a person who walks the path of karma yoga.