Life is something of a crapshoot. How much control do we really have over what happens to us? Where you're born, and to whom, have a huge influence on the rest of your life. That's not to say that these things determine the course of your life, but they can (and often do) play a significant role.
Beyond that, you can live your life the "right" way and circumstances can still fuck you over. You can study hard, go to college, and then the economy can tank right when you need a job. You can eat organic vegetables and hormone-free beef and you might still sprout tumors. You can nurture a fantastic relationship and it can still go to pieces.
I know you ultimately have the last say in how you react to these things. I know I'm being whiny, and have been for the past few days. It's just frustrating when there appears to be very little "justice," as we think of it, in the world at all.