One of the interesting things about magic is it is a lot more difficult for a spell to work, if the person it is being cast on doesn't believe in it, or actively is working against it. So one of the best things you can do is affirm to yourself "this spell has no power over me", and then do your best not to think about it too much. The more time and energy you spend thinking about it, the more power you are going to give it over you.
The link that ShannonCutinello gave is actually pretty helpful as well - cleansing baths (with sea salt and maybe a bit of sage as well for purification) are good at dispelling negative energies.
It is all in your mind. No spell or anything of the sort will work on you if you don't believe it. Remember, you are the master of your own destiny. No person or otherworldly force can affect you unless you allow it to happen.
You break it by waking up and realizing you are no longer an easily duped child, and that the maturity you've acquired with age provides you with a solid realization that spooks and spells aren't real.
If you believe in Jesus Christ and that he died for you, a spell cannot have any power over you because it is of satan. If you have a brief moment of fear, just say, "satan, get under my feet," and grind that spell into the dirt or gravel just as if you were putting out a cigarette. If God is for you, no one or no thing can come against you.