When we ignored an opportunity to help someone, we felt guilty. When we failed to do the work we were supposed to do, we felt depressed. Speaking harshly to someone, we became unsettled and agitated. This is cause and effect. We do something and we experience the consequences.  

Over time, and with awareness, we will discern patterns. When we act in certain ways, there are the same related feelings and results. As this pattern makes itself clear, we will realize that negative actions result in distress, while those that are positive result in contentment and peace.