"When I do good, I feel good, When I do bad, I feel bad."

-Abraham Lincoln

Everytime you do something bad, you will always feel bad about it, you will never feel good about that action. On the opposite, when you do something good, you will feel good about it and not bad.

When you study before a test, you will feel good once you do good on that test and when you don't study for that test, you did bad, then after that test you will feel bad.