To Do Good 
  "The best recreation is to do good" 
               -William Penn 

I think this means like when you do something right to be good for yourself.For example, if you do good in your classes you get a good grade and you be proud of yourself and even your parents. Another example, is that when you reach your goal and you graduated you be proud of yourself. That's why you always have to choose the right and not choosing the wrong because you never know if you will do something good and makes you feel good to yourself. Other example, is that if you help a person with something then they know that you're doing something good that make you feel good. And if you choose the wrong then you wont feel nothing because you know you're doing something wrong.