@genmaicha the accumulation of karma from past actions is stored in the casual body like the samskaras. like samskaras it lies dormant until the correct conditions arise for it to bear fruit. the part of the heap of past karma that is ripe is experienced in this lifetime. the part of this form of karma that is already "set in stone" (upon rebirth iirc) doesnt end for the yogi. however, currently being created karma to be experienced later ceases. for non-yogis, currently being created karma may join ripe karma for this lifetime or join the karma experienced in future lifetimes yet to bear fruit.
one way to transcend the play of karma is through desireless (selfless) action. by doing all things for God, one subverts the vicious cycle and aligns himself with the divine will. another, more difficult way is through renunciation of action, aka becoming a sannyasin.