That notion that our works influence our lives either for good or bad as a function of those Shramana concepts originating in India which propose that fate may be influenced by what we do or think.
Now me, I do my fair share of tempting fate and indeed karma has bit me in the butt on more than one occasion. It is a never ending circular thing which is said to be so basic to existence that we don't even notice it.
However, I have noticed those effects on more than one occasion and I must say I would prefer to cultivate good karma if at all possible.
Toward that end I attempt to think before I speak. Not act on impulse. Attempt to quell my obsessive compulsive inclinations and in general be less 'anal retentive' over time. I'm not always successful either and I have noticed those times when karmic success has eluded me ...
It makes for spiritual doldrums such as those I'm having now. Perhaps less profanity and more reading -- or at least TRY to be more acceptable in polite company.
You may think it humorous to consider behavior in activities of daily living. Laugh away. Get on the bad side of karma and you're in for a most unpleasant turn of events ... unless you're one of those who seems to escape it's influences. I've noticed this too. Self indulgent rude stupid people who flit through life totally unaware of any repercussions of that harm they have done to others.
I suppose the crux of karma is mostly that attempt to be more socially aware.