Thought Forms are negative thinking patterns that we can fall into after a particularly stressful event, for example a divorce or abuse. They can involve a negative attachment to a person, but they can also be a persistent negative association with some kind of trauma on any scale, ranging from a moment of pain to a car crash.
These Thought Forms once they fully take hold can take over many aspects of your life and lead to resentments, fear, anxiety and depression. The longer this negative energy stays within your system the more it grows and the bigger its effect will be on you. Thought Forms have the capacity then to make you quite ill.
The best way to protect yourself from Thought Forms is to keep yourself strong, healthy, happy and positive :o) Become aware of your thoughts, and the effect that they have on you emotionally, spiritually and even physically. By learning to get in touch with your higher self, or your intuition, you will find it much easier to stay aware of your thoughts. Amethyst is a great crystal for intuition and connection to the higher self. Meditation, focusing on opening your third eye and also working through any unresolved issues you may have, is also an excellent way to keep in touch with yourself.