Karma
How people treat you is their karma; how you react is yours.
On one hand, we know that everything happens for a reason, and there are no mistakes or coincidences. On the other hand, we learn that we can never give up, knowing that with the right tools and energy, we can reverse any decree or karma. So, which is it? Let the Light decide, or never give up? The answer is: both.
You can't connect the dots looking forward; you can only connect them looking backwards. So you have to trust that the dots will somehow connect in your future. You have to trust in something — your gut, destiny, life, karma, whatever. This approach has never let me down, and it has made all the difference in my life.
My mother believed in curses, karma, good luck, bad luck, feng shui. Her amorphous set of beliefs showed me you can pick and choose the qualities of your philosophy, based on what works for you.
There's a natural law of karma that vindictive people, who go out of their way to hurt others, will end up broke and alone.