I believe that people make mistakes. Sometimes, those can harm you or intrude on your life. You need to understand that sometimes there are things that you need to just accept and move on with your life.
Take, for example, road rage. If somebody cuts you off in traffic, you should just let it roll off your shoulders...don't let it bug you. Just forgive them - if you accidentally cut somebody off, wouldn't you want to be forgiven?
Try to put your past behind you...forgive the transgressions others have committed against you, in the hopes that others can forget those you've caused against them.