Unlike the physical world, in the spirit world there’s nobody outside of ourselves judging us or deciding what price we’re going to pay for our deeds. Ultimately, we are our only judges. Rather than dole out rewards or punishment, karma acts as a neutral accounting system, one that has the effect of balancing that which may previously have been out of balance.
Like the law of attraction, the law of karma says that every thought, word and action acts like a boomerang. Whatever we throw out there will eventually come back to us---just because that's the law. It might not look the same, but the lesson or the vibrational content will match. It may come back to us instantaneously, like the guilt we feel when we’ve hurt someone’s feelings (or the joy we feel when we've done something kind), or it may take lifetimes to manifest, but manifest it will.
The important thing to realize is that the process of karma is ultimately our friend. The hard-won lessons from our past have shaped us into better people today. Who we are now is the sum total of all our thoughts, words, and actions that came before. And if that's not a great comfort to you, don't worry. You can turn it all around right now----because this is the most important moment, the most relevant moment, there is.
Remember what the great Yogananda said, "A saint is a sinner who never gave up."