yes. for me Karma is a very powerful thing in my life. around me people often get what they deserve but its not realy three fold. Like some will say something mean to me and then they will hurt them selves in some way. it happens even when i dont want it to. the three fold law is always around and so is karma
Most belief systems have some sort of belief about consequences for your actions. They all differ in some way, but the rule is essentially that you need to take responsibility for yourself. The consequences are usually only metaphorical, as in the case of the threefold law. If you do not believe in it, then I do not see why it should affect you.