I think you are absolutely right! If you think bad thoughts, you will manifest them. Fearing being a nervous wreck will draw that kind of energy into your life. But that it why it is so important to meditate and dwell on positive thoughts! If you think good thoughts and consequently manifest good things, you will have no room for negativity in your life. Acknowledgement of the law (in a spiritual sense) is not meant to make one nervous or afraid, but capable of controlling their lives.

I recommend the book E-Squared by Pam Grout. She explains the law of attraction in a hilarious, very positive way that helped prove to me that I was capable of creating a positive environment for myself!