I have always believed in karma - both good and bad.
I know it may be a bit naive, but I honestly believe that when you do some selfless deed out of the pure goodness of your heart, whether it's large or small, something good will happen to you in return.
That's not to say you should only do good deeds in anticipation of receiving something in return.
Nevertheless, my karma has been a bit out of whack lately.
I went to a movie theater a few weeks ago on a Friday night, and apparently, my karma was so off that it came back to haunt me.