when you do good  you feel good- Abraham Lincoln 

 what i think this quote means is that you get the choice weather to do the right thing or the wrong thing. so when you you do the decision that is good or bad you are going to feel the same way cause you know what you have done in that event. for example if you steal you know it was bad and later on in your life that event can get to you and make you feel bad because what happens if someone need that object you robbed  but.when you do something good then you know you did  the good thing and that makes you feel better about yourself.