The Value of Repentance

I have been reflecting on repentance: what is its true value? One that I can think of is that it promotes a total responsibility for all that has come about in life. But repentance is not easy. For instance, I might superficially accept the things that have happened to me as coming from my previous karma, but that acceptance is only half-heartedly so, or perhaps even begrudging. If I am resigned in my attitude toward my present life, how can that really be "repentance' in any sense of the word? I think to really repent requires a deep appreciation that this life perfectly matches/meshes with one's previous karma, and can be a powerful way to learn from it.
  For example, if I think of karma as a punishment, my attitude will be that of a helpless person who is angry or resentful. I carry the sense that someone else is deliberately trying to punish me. On the other hand, if I think of karma as the inevitable result of causes and conditions that never fail, I can take a much more curious, even scientific approach to it. Knowing that this karma is a "natural" result of previous actions, what can I do differently? Or, what can I really learn and reflect based on what's given to me now? If I am not in tune with this idea, I will naturally feel a kind of begrudging sense that some being (a parental figure or deity perhaps) has deliberately put me in this situation. In reality, the situation is none other than the result of many past conditions.
  I have influence in terms of my attitude: not seeing this in a resigned way, but seeing it from the perspective of an explorer: what new things can I learn from this situation ? How might I develop more flexible strategies? What do I need to let go of? It's important, at least from my point of view, to explore the idea of karma as a kind of learning, rather than as a strict punishment that is designed to make a person feel bad.