"When I do good, I feel good. When I do bad, I feel bad."- Abraham Lincoln
What Lincoln is trying to tell us that by doing good you will feel better about yourself and when you do bad you might regret about it later. For example when you do bad, you may have hurt someone or got them in trouble, like when you steal from the store and owner will blame a employee for not keeping his eye out and they might lose their job.Also you may have gotten in a physical fight with someone you will probably gave him a serious injury that he might not recover from.