Here's another thought to add to the mix:

Sometimes due to misunderstanding the doctrine of karma one has a tendency to blame everything on karma and try to exonerate oneself from responsibility or from the need to take personal initiative. One could quite easily say, "This is due to my negative past karma. What can I do? I am helpless."

This is a totally wrong understanding of karma, because although one's experiences are a consequence of one's past deeds, that does not mean that one has no choice, nor that there is no room for initiative to bring about change. This is the same in all areas of life. One should not become passive and try to excuse oneself from having to take personal initiative on the grounds that everything is a result of karma. If we understand the concept of karma properly, we will understand that karma means "action," and is a very active process"--

His Holiness the Dalai Lama, from "Healing Anger", published by Snow Lion Publications.