"I am the owner of my karma .
I inherit my karma.
I am born of my karma.
I am related to my karma.
I live supported by my karma.
Whatever karma I create, whether good or evil, that I shall inherit."
, Anguttara Nikaya V.57 - Upajjhatthana Sutta
Let's take a look at Karma
"I don't understand why this is happening to me"
Karma is a word from the Sanskirt language, it means "action". In Buddhism karma refers to your intention or motivation while doing an action. In the West we think that Karma is what happens to us, that is wrong. Karma is what we do, or how we react to something. The Sanskrit word for the effects or results of karma is 'vipaka'. Karma is like a seed, it is what we plant by an action that we have done. A pleasant action creates a pleasant or virtuous merit seed, an unpleasant action will plant an unpleasant or non-virtuous merit seed. These seeds are planted into our mental continuum. This seed will ripen later when the proper causes and conditions are present, and come as a situation directed at us. This situation could be pleasant or unpleasant depending on what kind of karmic seed is ripening at that time. How we react to this situation will plant yet another karmic seed, the cycle continues on and on. What is happening to us today was a karmic seed planted long ago.
The idea of karma is not just an eastern thought:
Do not be deceived: God cannot be mocked. A person reaps what he sows.
All things whatsoever you would that men should do to you,
do even so to them: for this is the law and the prophets.
How is Karma formed?
I was asked how karma was formed, it is started by a thought, an intention and moves on from there. Take a little "white" lie or over exaggeration, it builds on itself causing the karma to come back at you as someone lying to you, or someone finding out about the lie and then not trusting your word anymore. A little white lie can change how people see and think of you. Or the other way, a kind true word, a kind intention, without expecting anything in return, the energy grows, surrounding you with positive vibes, making you happy, at ease. All your actions have repercussions, and it all starts as a thought. Watch your mind, meditation is the key to catching your thoughts before they turn into action, which may be old karmic seeds that are ripening. You can stop the cycle of habitual habits.
How does Karma manifest
How often do we say, that made me angry, or this hurt me..... When anger(or any emotion) arrises it is because we already have that karmic seed within us, when the conditions are right the seed ripens, and we feel that emotion. How did those seeds get there, we put them there through past action, they are now a part of our mental continuum. If you did not have that seed within you that situation would not produce anger. Think about it, in the same situation one person gets angry, but another feels compassion. If it was the situation that caused the feeling both should feel the same emotion. How you respond and feel has nothing to do with outside circumstance. Stop blaming others or circumstances for your emotions, you are responsible for your karmic seeds. Through meditation you can change these habitual patterns.