"When I do good, I feel good. When I do bad, I feel bad."
      -Abraham Lincoln

This quote is trying to say that whatever you do, you will feel either good or bad depending in what you did. 
*For Example: 
-If you give food to a Homeless, you will feel great because that is such a Nice thing. 
-In other hand, if you kill someone, you will feel bad. Maybe not that moment but, you will because that is a bad thing.