In struggling to understand the working of the Karma process, care must be taken to not lose sight of the meaning of the Law of Karma as it applies to existence in the form of human life. Karma is the consequential aspect of the reincarnation cycle. Essentially, Karma is the "bottom line" of the conduct of one's past and present lives that determines the circumstances for future lives.
Karma is the moral law of retribution. It is not retribution in terms of punishment-reward, rather it is justly deserved payment in return. Karma is not good-bad, credit-debit, judgment or fate. It is not a thing, a characteristic or a situation. It is not generated or dissipated. It cannot be directed or altered. One does not give, get or possess Karma. It is the law of cause and effect or ethical causation. The Law of Karma is like the Law of Gravity. It is everywhere, a fact of the reality of existence. It is part of the evolutionary process of the universe.
Karma is an extension of the concept that every seemingly individual thing is part of a universal oneness. That is, all events are interrelated: every cause has an effect, which itself becomes cause for effect that may eventually return to act upon its source. Along with actions and events, the universal oneness includes things of material substance. The principle of matter-energy equivalence is fundamental in both the science of physics and the pursuit of spiritual wisdom.
The present comes from the past. The here and now of any moment or situation is the complex result of an infinite chain of events large and small, direct and distant. The present circumstances of any being, whether unpleasant or fortunate, are the working of Karma. The circumstances and Karma may be viewed as one and the same, or distinct, Karma a process, the circumstance its result.
Karmic forces that shape the effects of future events do not necessarily act quickly; they usually build out over time in very complex ways. The consequences of Karma in a human life are almost always the result of many lifetimes and not just a single lifetime of a single being, but the interrelated lives of many individuals. Consider just one facet of the evolutionary process: the number of people involved in an individual's direct line of ancestry. The present is the sum total of the past, and a human individual is the product of those who came before.
Going back ten generations, a person carries the characteristics of over 2000 people. Not just biological attributes, but centuries of behavioral and culture traditions that parents imprint upon their infants until puberty. Add to this the cultural, behavioral, intellectual and environmental traits acquired by an adult prior to parenthood, and it can be seen that each of us carries the influence of probably no less than 10,000 other individuals along with our own experiences in this and previous lives. This is the basis for the idea of group Karma, but the freedom to act and responsibility therefor lies with, and only with, the individual.
Every act of every being will have subsequent effective action upon its originator, if not immediately then at some time in this life or a future life. This is the moral doctrine of Karma: evil begets evil; good begets good. "What goes around, comes around." "As ye sow, so shall ye reap." Suffice it to say that a life well lived is rewarded with conditions in a future life that enable even further benefit, and that an ill-behaved life will earn a posterity in which the balance of opportunity favors a harsh reality where the hard comes easier and the easy is harder.
Every action is directed by thought arising from desires of either internal or external origin. Most of our daily acts have immediate effect for maintaining existence and are neither good nor evil, but they are still subject to the Law of Karma. Seemingly innocuous deeds may have long-term effects of which we may never be aware but which will result just the same. We create and control our own Karma by thoughts and actions, most of which arise from a lives-long accumulation of habits. We are creatures of habit, of which for the most part we are not conscious. To be aware of one's habits is a step forward, but that's another subject.